Cell Biology Exam # 3 Review

PLCb-IP3

ACh-stimulated NO production signals through ____________

e) dissociation of Pi

After a myosin motor head has been "cocked" and is bound to the actin filament, which of the following events triggers the "power stroke" a) ATP hydrolysis b) GTP hydrolysis c) binding of ATP d) binding of GTP e) dissociation of Pi

b) ATP hydrolysis ==> "cocks"

After release of the myosin head from an actin filament, which of the following events "cocks" the myosin head into the active conformation. a) binding of ATP b) ATP hydrolysis c) dissociation of ADP d) dissociation of Pi e) none of the above

d) taxol actually stabilizes microtubules

Agents that interfere with the dynamic instability of microtubules, including taxol, cholchicine, and vincristine, are effective anti-cancer chemotherapeutics. Why is taxol less toxic to normal cells? a) taxol can be administered orally b) taxol promotes the formation of gamma tubulin ring complexes c) taxol works at a lower concentration d) taxol actually stabilizes microtubules

c) Go

An extracellular messenger molecule that increases intracellular calcium levels in target cells, AND is blocked by pertussis toxin, probably signals through which of the following trimeric G-proteins? a) Gs b) Gi c) Go d) Gq e) Gt

e) all of the above

Apoptosis can be induced by which of the following? a) pro-caspase activation b) expression of some Bcl-2 family genes c) suppression of other Bcl-2 family genes d) release of cytochrome C from mitochondria e) all of the above

a) cdc25

At the M-phase checkpoint, which of the following proteins is the phosphatase that removes the inhibitory phosphate group from M-Cdk complex? a) cdc25 b) wee1 c) cdc20 d) cdc6

d) ubiquination of cyclin B

At the anaphase checkpoint, which of the following events must occur for mitosis to proceed? a) phosphorylation of securin b) ubiquination of APC c) phosphorylation of cyclin B d) ubiquination of cyclin B e) none of the above

a) actin polymerization

At the leading edge of a motile cell, which of the following events provides the force that drives the lamellipodium forward? a) actin polymerization b) GTP hydrolysis c) microtubule polymerization d) ATP hydrolysis

a) securin

At the metaphase-anaphase checkpoint, anaphase promoting complex (APC) ubiquinates which of the following proteins to release separase from inhibition? a) securin b) cyclin B c) secludin d) cdc20

a) cyclin B

At the metaphase-anaphase transition, which of the following proteins is ubiquinated by APC? a) cyclin B b) cdc20 c) separase d) cohesins e) none of the above are ubiquinated by APC

a) cyclin B

At the metaphase-anaphase transition, which of the following proteins is ubiquinated by APC? a) cyclin B b) cdc20 c) separin d) cohesins e) none of the above are ubiquinated by APC

c) G1 phase

At which phase of the cell cycle do the SMC protein complexes that prevent premature separation of sister chromatids first assemble around DNA? a) M phase b) G2 phase c) G1 phase d) S phase

Calcium-Calmodulin-dependent Protein kinase (CaM kinase)

CaM kinase ie. Calmodulin (one of many calcium binding proteins)

Export: 1) Na+-driven & Ca2+ exchanger 2) Ca2+-pump Sequestration: 1) Ca2+-pump in ER membrane 2) Ca2+-binding molecules in cytoplasm 3) active Ca2+ import in mitochondrion

Calcium Homeostasis is maintained by what two methods?

endoplasmic reticulum

Calcium activated calcium channels drive propagation of calcium "waves" along the ______________

arginine ie. ADP Ribosylation

Catalyzed by enzymes, called mono- (or poly-) ADP ribosyltransferases, transfer of one (or more, in a chain) ADP ribose moieties to ____________ residues on target proteins

Rhodopsin 11 cis retinal cGMP light cilium discs rods & cones

Cell Signaling Events in the Retina include.........

signaling by --> protein phosphorylation & by --> GTP-binding protein

Common events in cell signaling

b) dimeric, minus(-) end directed microtubule motor proteins

Complete the following sentence. "Cytoplasmic dyneins are ... " a) dimeric, plus(+) end directed microtubule motor proteins b) dimeric, minus(-) end directed microtubule motor proteins c) trimeric, plus(+) end directed microtubule motor proteins d) trimeric, minus(-) end directed microtubule motor proteins e) components of the nuclear envelope

b) minus(-) end directed microtubule motor proteins

Complete the following sentence. "Most kinesins are ... " a) plus(+) end directed microtubule motor proteins b) minus(-) end directed microtubule motor proteins c) plus(+) end directed actin motor proteins d) minus(-) end directed actin motor proteins e) inactive structural proteins

e) proteases

Complete the following sentence: Caspases are ...... a) kinases b) phosphatases c) ubiquitin ligases d) scaffold proteins e) proteases

a) proteases

Complete the following sentence: Caspases are ...... a) proteases b) phosphatases c) ubiquitin ligases d) scaffold proteins e) kinases

e) a mechanism that is not listed above --> binding pro-apoptotic BAX, BAK and BH3-only proteins. "this promotes mitochondrial outer membrane permeability and induces leakage of cytochrome C out of the mitochondria to cause cell death through apoptosis"

Complete the following sentence: The anti-apoptotic protein, Bcl2, prevents apoptosis by a) returning cytochrome C to the mitochondrion b) promoting the aggregation of "BH123" proteins c) promoting the aggregation of "BH3 only" proteins d) preventing the aggregation of "BH3 only" proteins e) a mechanism that is not listed above

c) preventing the aggregation of "BH123" proteins

Complete the following sentence: The anti-apoptotic protein, Bcl2, prevents apoptosis by .... a) returning cytochrome C to the mitochondrion b) promoting the aggregation of "BH123" proteins c) preventing the aggregation of "BH123" proteins d) preventing the aggregation of "BH3 only" proteins e) Bcl2 protein actually promotes apoptosis

a) prometaphase

Disintegration of the nuclear lamina and the nuclear envelope occurs during which phase of mitosis? a) prometaphase b) meta phase c) anaphase d) prophase

d) p53

During G1 phase, which of the following prevents entry into S-phase when DNA damage is present? a) mTOR b) cdh1 c) cdc20 d) p53 e) myc

d) P53

During Gl phase, which of the following prevents entry into S-phase when DNA damage is present? a) mTOR b) Hct1 c) cdc20 d) P53 e) Myc

a) ORC

During S-phase, which of the following is phosphorylated by S-Cdk complex to prevent a second round of DNA synthesis? a) ORC b) cdc6 c) cdc25 d) Rb

b) it leaves through channels formed by "BH123" proteins

During apoptosis, how does cytochrome C get out of the mitochondrion? a) it leaves through channels formed by "BH3 only" proteins b) it leaves through channels formed by "BH123" proteins c) it aggregates to form clusters that are membrane permeable d) it binds to BH123 proteins and enters the cytosol e) it binds to Bcl2

e) myosin II

During cytokinesis, which of the following motor proteins closes the contractile ring? a) dynein b) kinesin c) dynamin d) myosin I e) myosin II

e) when the microtubule looses it's "GTP cap" ==> "catastrophic" shortening

During dynamic instability of microtubules, when does the "catastrophic" shortening of microtubules occur? a) when GTP levels are exhausted b) when ATP levels are exhausted c) when microtubules contact the plasma membrane d) when the ATP-bound form of G-actin falls below the critical concentration e) when the microtubule looses it's "GTP cap"

b) the neck linker "zippers" onto the leading head

During kinesin movement along a microtubule, what happens immediately after nucleotide exchange? a) the motor head releases the microtubule b) the neck linker "zippers" onto the leading head c) the trailing head dissociates d) the leading head binds tightly e) the leading head is thrust forward

d) exchange of ADP for ATP

During kinesin movement along a microtubule, which event causes the neck linker to "zipper onto the head domain" (i.e., the "Power Stroke") a) hydrolysis of GTP b) dissociation of Pi c) hydrolysis of ATP d) exchange of ADP for ATP e) exchange of GDP for GTP

d) dissociation of Pi

During movement of myosin motor proteins along actin filaments, which of the following events results in "power stroke"? a) ATP binding b) ATP hydrolysis c) ATP exchange d) dissociation of Pi

b) ATP binding

During movement of myosin motor proteins along actin filaments, which of the following events results in release of the motor head from the actin filament? a) dissociation of Pi b) ATP binding c) ATP hydrolysis d) ATP exchange

a) binding of ATP ==> "release"

During myosin movement along an actin filament, which event causes release of the head domain from the actin filament. a) binding of ATP b) hydrolysis of GTP c) hydrolysis of ATP d) dissociation of ADP e) dissociation of Pi

c) binding of ATP

During myosin movement along an actin filament, which event causes release of the head domain from the actin filament. a) hydrolysis of ATP b) hydrolysis of GTP c) binding of ATP d) dissociation of ADP e) dissociation of Pi

c) ATP exchange for bound ADP on the leading head

During the movement of a kinesin dimer along a microtubule, which of the following events is responsible for the "power stroke" a) ATP hydrolysis on the leading head b) ATP binding and Pi release on the trailing head c) ATP exchange for bound ADP on the leading head d) ADP dissociation on the trailing head

b) cyclin B

Failure of anaphase promoting complex (APC) to ubiquinate this protein would result in arrest of cell cycle at anaphase. Which of the following is this protein? a) secludin b) cyclin B c) securin d) cdc20

Gt (alpha)

G-protein diversity: _________ activates a phosphodiesterase

Gi (beta/gamma)

G-protein diversity: __________ activates potassium channels

Go (alpha)

G-protein diversity: __________ inactivated by pertussis toxin

Gi (alpha)

G-protein diversity: __________ inhibits adenylyl cyclase & is inactivated by pertussis toxin

Gs (alpha)

G-protein diversity: __________ stimulates adenyly cyclase [activated by cholera toxin]

Go (a&bg) activates phospholipase Cb

G-protein diversity: ___________ activates phospholipase Cb

Gq (alpha) activates phospholipase Cb

G-protein diversity: ______________ activates phospholipase C-beta

a) mTOR

Growth factors increase protein synthesis and decrease protein degradation by activating which of the following? a) mTOR b) cdh1 c) cdc20 d) p53 e) myc

d) TOR

Growth factors signal through the AKT kinase, resulting in the phosphorylation and activation of which of the following? a) MAP kinase b) BAD c) STATs d) TOR

c) by activating the Fas death receptor on target cells

How do activated T-cells initiate apoptosis via the extrinsic pathway? a) by promoting the release of cytochrome C in target cells b) by releasing destructive cytokines c) by activating the Fas death receptor on target cells d) by blocking survival receptors on target cells

d) by promoting the synthesis of Cdk inhibitors

How does P53 activation prevent entry into S-Phase? a) by phosphorylating S-cdk b) by promoting the expression of cyclin E c) by inhibiting APC d) by promoting the synthesis of Cdk inhibitors e) P53 activation does not prevent entry into S-phase

a) by binding to and inhibiting E2F transcription factor

How does RB protein prevent escape from G0? a) by binding to and inhibiting E2F transcription factor b) by binding to and inhibiting P53 c) by phosphorylating P53 d) by binding to Cdk inhibitors like P21 e) actually, RB protein promotes escape from G0

a) by binding to and inhibiting E2F transcription factor

How does RB protein prevent escape from G0? a) by binding to and inhibiting E2F transcription factor b) by binding to and inhibiting p53 c) by phosphorylating p53 d) by binding to Cdk inhibitors like p21 e) RB protein promotes escape from GO

c) by leaving through channels in the outer membrane formed by BH123 proteins

How does cytochrome C escape mitochondria to promote apoptosis? a) by activating mitochondrial caspases b) by forming a lipid-soluble complex with BH123 proteins c) by leaving through channels in the outer membrane formed by BH123 proteins d) by diffusing through the disrupted mitochondrial outer membrane

d) it promotes the aggregation of initiator procaspases

How does cytochrome C initiate apoptosis? a) it promotes the aggregation of BH123 proteins in the outer membrane b) it aggregates to form channels in the outer mitochondrial membrane c) it directly activates executioner procaspases d) it promotes the aggregation of initiator procaspases e) none of the above

d) it promotes the recruitment of initiator procaspases

How does cytochrome C initiate apoptosis? a) it promotes the aggregation of BH123 proteins in the outer membrane b) it aggregates to form channels in the outer mitochondrial membrane c) it directly activates executioner procaspases d) it promotes the recruitment of initiator procaspases e) none of the above

c) by promoting the aggregation of initiator procaspases

How does cytochrome C promote apoptosis via the intrinsic pathway? a) by sequestering and inhibiting Bcl2 anti-apoptotic proteins b) by directly activating executioner procaspases c) by promoting the aggregation of initiator procaspases d) by disrupting electron transport resulting in death of mitochondria

b) by phosphorylating the BAD protein and releasing the anti-apoptotic protein, Bcl2

How does the Akt kinase inhibit apoptosis? a) by phosphorylating and inhibiting cytochrome C b) by phosphorylating the BAD protein and releasing the anti-apoptotic protein, Bcl2 c) by preventing the aggregation of BH123 proteins in the mitochondrial outer membrane d) by phosphorylating and activating inhibitors of apoptosis (IAPs)

d) by preventing the aggregation of "BH 123" proteins

How does the anti-apoptotic protein, Bcl2, prevent apoptosis? a) by promoting the aggregation of "BH 123" proteins b) by phosphorylating the BAD protein c) by preventing the aggregation of "BH3 only" proteins d) by preventing the aggregation of "BH 123" proteins

a) in the lamellipodium

In a motile cell, where would you expect to find the highest concentration of the ARP complex? a) in the lamellipodium b) in the cortex c) in the nucleus d) at the trailing end of the cell e) in the centrosome

d) at the leading edge

In a motile keratocyte, where would you expect to find most of the ARP2/3 complex? a) at the trailing edge b) near the centrosome c) near stress fibers d) at the leading edge

b) determines the substrate specificity of the kinase

In addition to the activation of the cyclin-dependent protein kinase, what is the role of the cyclin subunit? a) masks phosphorylation sites on the kinase b) determines the substrate specificity of the kinase c) determines the half life of the kinase d) prevents inactivation of the kinase

c) receptor dimerization

In order to signal through a receptor tyrosine kinase, substrate binding must accomplish which of the following? a) receptor internalization b) binding of a G-protein c) receptor dimerization d) phosphorylation of a G-protein

CREB "cAMP Regulatory Element Binding protein" ***PKA can activate gene expression by phosphorylating the CREB

In some cases, PKA enters the nucleus, where it phosphorylates other target proteins, including transcription factors like ____________

dark dark current ie. cGMP-gated Na+ channel in open position

In the __________, the cytosolic concentration of cGMP is very high due to high activity of guanylyl cyclase. cGMP activates ligand-gated Na+ channels, holding the channels open, resulting in a "_________________" of Na+ influx

a) cAMP levels go up

In the lab, you have cultured cells that express a trimeric G protein of the Gi family. Which of the following best describes the expected result of pertussis toxin treatment on these cells? a) cAMP levels go up b) cAMP levels go down c) cGMP levels go up d) IP3 levels go up e) IP3 levels go down

calcium wave production

Intensity of signaling event is encoded in frequency of .........................

False ....why?

Is the following statement TRUE or FALSE? "Only the alpha subunit of a trimeric G-protein is capable of signaling to downstream effectors."

JAK = JAnus Kinase STAT = Signal Transducer and Activator of Transcription 1. Prolactin & Cytokines signal through the JAK-STAT Pathway 2. Cytokine receptors recruit cytoplasmic tyrosine kinases = JAKs 3. Binding of ligand causes dimerization and activation of JAKs 4. JAKs phosphorylate one another and the receptors 5. Phosphotyrosines on receptors recruit STATs 6. STATs are phosphorylated by JAKs and dimerize 7. Active STAT dimers are escorted across the NPC 8. They bind to specific regulatory elements on DNA, and 9. Recruit components of the transcription apparatus 10.Resulting in increased expression of relevant genes

JAK-STAT Signaling Pathway .......... ie. Enzyme-Coupled Receptor Signaling Strategies --> Direct activation of latent transcription factors

b) STATs

Janus kinases phosphorylate which of the following signal transduction proteins? a) CREB b) STATs c) IP3 d) MAP kinases e) none of the above

Gt ie. Cell Signal Cascade in the Retina

Light drives the photoisomerization of 11-cis retinal to all-trans retinal, which activates Opsin. Opsin activates ___________ (also called "transducin")

Mitogen Activated Protein (MAP) ie. MAP Kinase Pathway --> Scaffold proteins recruit appropriate kinases

MAP ie. G-protein-mediated activation of protein kinases

a) Maturation Promoting Factor

MPF refers to the substance(s) present in the cytosol of Xenopus oocytes that is capable of driving multiple cycles of M phase and S phase in vitro. What is MPF? a) Maturation Promoting Factor b) Mamma's Powerful Force c) Mitotic Progress Facilitator d) Metaphysical Procreation Factor

e) Maturation Promoting Factor

MPF refers to the substance(s) present in the cytosol of unfertilized Xenopus oocytes that is capable of driving multiple cycles of M phase and S phase in vitro. What is MPF? a) Mitotic Progress Facilitator b) Metaphase Promoting Factor c) Mamma's Powerful Force d) Metaphysical Procreation Factor e) Maturation Promoting Factor

d) Maturation Promoting Factor

MPF refers to the substance(s) present in the cytosol of unfertilized Xenopus oocytes that is capable of driving multiple cycles of M phase and S phase in vitro. What is MPF? a) Momma's Powerful Force b) Metaphysical Procreation Factor c) Mitotic Progress Facilitator d) Maturation Promoting Factor e) None of the above

e) drugs that disrupt the dynamic instability of microtubules

Many anti-cancer drugs target the microtubule cytoskeleton. Which of the following best describes this class of anti-cancer drugs? a) drugs that destabilize microtubules b) drugs that stabilize microtubules c) drugs that prevent microtubule polymerization d) drugs that promote microtubule polymerization e) drugs that disrupt the dynamic instability of microtubules

c) Rb

Mitogens promote entry into cell cycle by inactivating which of the following proteins? a) cdc20 b) p53 c) Rb d) cyclin D e) APC

"BAD" 1. BAD is an inhibitor of the anti-apoptotic protein Bcl2 2. Phosphorylation of BAD releases (activates) Bcl2 3. Cell does not commit suicide

One important substrate for the Akt kinase is "________"

glutamic acid ie. Cell Signal Cascade in the Retina

Outer segment membranes are relatively depolarized in the dark. Light exposure causes transient hyperpolarization, resulting in decrease neurotransmitter release. Neurotransmitter is _____________

Pleckstrin Homology (PH) Domain

PH domain

Phosphoinositide 3 (PI-3) ie. Direct activation of phospholipid kinases

PI-3

PI 4,5 bisphosphate (PIP2) ie. in Activation of Phospholipase C by GPCRs

PIP2

Ser-Thr Kinase

PKA is a __________________

ie. Enzyme-Coupled Receptor Signaling Strategies: --> Direct activation of phospholipid kinases PI 3,4,5 trisphosphate serves as a binding site for recruitment and assembly proteins with PH domains The Akt Kinase binds to PI 3,4,5 trisphosphate, as do various other kinases, some of which phosphorylate & activate the Akt Kinase

Phosphoinositide 3 (PI-3) Kinase Signaling

d) it promotes the release of Ca2+ from the ER

Phospholipase Cβ activation leads to the production of (at least) two signaling molecules; inositol 1,4,5-trisphosphate (IP3) and diacylglycerol. What is the function of IP3? a) it activates adenylyl cyclase b) it recruits protein kinase C to the plasma membrane c) it phosphorylates PIP2 d) it promotes the release of Ca2+ from the ER e) none of the above

e) drugs that have any of the above actions should be considered potential anticancer agents

Potential anticancer drugs might include agents that do which of the following? a) prevent the polymerization of microtubules b) prevent the de polymerization of microtubules c) promote the depolymerization of microtubules d) inhibit GTP hydrolysis at the plus (+) end of microtubules e) drugs that have any of the above actions should be considered potential anticancer agents

a) JAK-STAT pathway

Prolactin and some cytokines alter gene expression through which of the following signal transduction pathways? a) JAK-STAT pathway b) MAP kinase pathway c) Pl-3 kinase pathway d) Delta-Notch pathway

Receptor Tyrosine Kinases (RTKs) 1. Extracellular messenger (usually dimeric protein complex) binds 2. Causing dimerization of the RTK 3. Dimerization actives intrinsic kinase domains on both RTKs 4. RTK proteins phosphorylate themselves & each other [called "autophosphorylation"] 5. Phosphotyrosine residues serve as binding sites for the recruitment of components of the signaling complex

RTKs

1. Mitogen binds to RTK dimer -- activates RTK 2. Ras GTPase is tethered to the plasma membrane 3. Ras activating protein serves as a GEF

Receptor Tyrosine Kinase (RTK) Signaling through Ras

tyrosine kinase ie. ENZYME-COUPLED RECEPTORS

Receptor dimerization activates _______________________ activity (intrinsic or recruited)

d) When the microtubule loses its GTP cap

Regarding microtubules, when does "Catastrophe" occur? a) When the cell runs out of GTP b) Usually on the second Tuesday in November c) When microtubules reach a certain age d) When the microtubule loses its GTP cap e) When the microtubule binds to a plus(+) end capping protein

c) loss of cilia

Removal of the of the centrioles from a eukaryotic cell would result in which of the following? a) disruption of actin cytoskeleton b) disruption of microtubule cytoskeleton c) loss of cilia d) necrosis e) apoptosis

amplifiers ie. one rhodopsin molecule absorbs one photon then --> 500 G-protein (transducin) molecules are activated then --> 500 cyclic GMP phosphodiesterase molecules are activated then --> 10^5 cyclic GMP molecules are hydrolyzed then --> 250 cation channels close then --> 10^6-10^7 Na+ ions per second are prevented from entering the cell for a period of ~ 1 second --> membrane potential is altered by 1 mV finally ==> SIGNAL RELAYED TO BRAIN

Rod/Cone outer segments act as signal ____________

phosphodiesterase

Signaling is terminated by a ______________ in the Activation of cAMP-dependent protein kinase (PKA) pathway.

e) Akt kinase

Some of the effects of growth factors are mediated through which of the following kinases? a) protein kinase A b) protein kinase C c) CAK d) Wee1 kinase e) Akt kinase

1. Receptor-ligand binding stabilizes the active conformation of the receptor, and 2. Increases affinity for GDP-bound trimeric G-protein complex 3. Occupied receptor binds tightly to G-proteins 4. Active receptor conformation acts as GEF, which facilitates exchange of GDP for GTP on a-subunit of trimeric G-protein 5. Binding of GTP alters conformation of the a-subunit 6. ... activating both the a-subunit and the bg-complex 7. In some cases, the a-subunit and the bg-complex separate and activate separate signaling pathways

Steps involved in G-Protein Coupled Receptors

b) phosphatidyl inositol 3,4,5-trisphosphate

The AKT kinase is recruited to the plasma membrane by which of the following membrane associated molecules? a) diacylglycerol b) phosphatidyl inositol 3,4,5-trisphosphate c) Ras d) actin

a) Akt kinase

The PI3 kinase signaling pathway results in the activation of which of the following protein kinases? a) Akt kinase b) protein kinase A c) protein kinase C d) Janus kinases e) M-Cdk

Nuclear Lamina --> form a fine meshwork of fibers

The ___________ provides structural support for the nuclear envelope.

K+ Channel (Kir) ie. Heart Muscle Cell "Metabotropic" receptor M2 muscarinic cholinergic receptor w/ G-protein coupled receptor

The beta/gamma complex opens a __________ Channel which reduces contraction

b) ADP ribosylation of the alpha subunit

The effect of pertussis toxin treatment on trimeric G-protein signaling is due to which of the following covalent modifications? a) ubiquitination of the alpha subunit b) ADP ribosylation of the alpha subunit c) phosphorylation of the alpha subunit d) phosphorylation of the beta-gamma complex e) dephosphorylation of the beta-gamma complex

GDP-Bound ***Note that the alpha and gamma subunits are anchored to the plasma membrane

Trimeric G-Protein in the Inactive "___________" State

True

True of False? "All myosin motor proteins move toward the plus(+) end of actin filaments."

Nuclear: --> nuclear lamins = in all animal cells Cytoplasmic: --> keratins = in epithelial --> vimentin and vimentin-related = in connective tissue, muscle cells, and glial cells --> neurofilaments = in nerve cells

Types of intermediate filaments:

c) depolymerization

Un-capped actin filaments "grow" (polymerize) at the plus (+) end. What happens at the minus end? a) ATP hydrolysis b) catastrophe c) depolymerization d) GTP hydrolysis

b) focal adhesions

Vinculin, together with Talin dimers, couple integrin dimers to the actin cytoskeleton in which of the following cell-matrix junctions ? a) desmosomes b) focal adhesions c) tight junctions d) adherens junctions e) gap junctions

ion-channel-coupled G-protein-coupled (largest family) Enzyme-coupled

What are 3 types of cell surface receptors?

a) proteases that cleave substrates at specific aspartate residues

What are Caspases? a) proteases that cleave substrates at specific aspartate residues b) phosphatases that dephosphorylate phosphotyrosine residues c) proteases that cleave substrates at specific glutamate residues d) phosphatases that dephosphorylate phosphothreonine residues

e) kinetochore microtubule catastrophe

What is the energy source that drives chromosomal segregation during anaphase A? a) The Force b) ATP hydrolysis c) GTP hydrolysis d) hydrolysis of cohesins e) kinetochore microtubule catastrophe

b) ATP hydrolysis

What is the energy source that drives chromosomal segregation during anaphase B? a) the electrochemical gradient across the plasma membrane b) ATP hydrolysis c) GTP hydrolysis d) catastrophic shortening of kinetochore microtubules e) the energy source is not known

e) they nucleate polymerization of microtubules

What is the function of gamma tubulin ring complexes? a) they stabilize the plus ends of microtubules b) they destabilize the plus ends of microtubules c) they stabilize the minus ends of microtubules d) they bind together the plus ends of microtubules e) they nucleate polymerization of microtubules

b) it prevents catastrophic shortening of the microtubule

What is the function of the "GTP Cap" on microtubules a) it is a binding site for kinesin motors b) it prevents catastrophic shortening of the microtubule c) it prevents the hydrolysis of GTP by the alpha subunit d) it prevents the hydrolysis of GTP by the beta subunit e) it is of no consequence

d) it is required for production of cilia

What is the function of the centriole? a) it is required for the production of microtubules b) it is required for the production of the spindle complex c) it is required chromosomal segregation d) it is required for production of cilia e) it has no known function

b) it binds to APC to promote G1

What is the role of Hctl in the cell cycle? a) it prevents initiation of S phase b) it binds to APC to promote G1 c) it inhibits P53 d) it is a component of the pre-initiation complex e) it is a transcription factor

d) determines the substrate specificity of the kinase

What is the role of the cyclin component of Cdk complexes (e.g., M-Cdk)? a) phosphorylates and activates the kinase b) dephosphorylates and activates the kinase c) prevents phosphorylation of the inhibitory site of the kinase d) determines the substrate specificity of the kinase e) none of the above

e) it determines the substrate specificity of the kinase

What is the role of the cyclin component of a cyclin-dependent protein kinase complex? a) it phosphorylates and activates the kinase b) it blocks the active site of the kinase c) it protects the kinase from ubquination d} it is a phosphatase e) it determines the substrate specificity of the kinase

d) it blocks myosin binding sites on actin filaments

What is the role of tropomyosin in striated muscle contraction? a) it activates myosin light chain kinase b) it transmits action potentials to myofibrils c) it opens calcium channels on the sarcoplasmic reticulum d) it blocks myosin binding sites on actin filaments e) it binds calcium and moves tropomyosin off myosin binding sites

d) it blocks myosin binding sites on actin filaments

What is the role oftropomyosin in striated muscle contraction? a) it is the minus(-) end capping protein in striated muscle b) it transmits action potentials to myofibrils c) it opens calcium channels on the sarcoplasmic reticulum d) it blocks myosin binding sites on actin filaments e) it binds calcium and exposes myosin binding sites on actin filaments

c) sarcomere

What is the smallest contractile unit in striated muscle cells? a) sarcophagus b) sarcoplasmic reticulum c) sarcomere d) thick filament e) myofibril

c) sarcomere

What is the smallest contractile unit in striated muscle cells? a) sarcophagus b) sarcoplasmic reticulum c) sarcomere d) sarcaster e) myosome

b) condensins

What is the term for the SMC protein complexes that gather and pack newly replicated DNA into chromosomes? a) cohesins b) condensins c) gatherins d) nucleosomes

b) sarcomere

What is the term for the smallest contractile unit of skeletal muscle? a) sarcosome b) sarcomere c) myofibril d) myofilament

d) they are consumed by macrophages

What is the ultimate fate of apoptotic cells? a) they aggregate in tissue to form scars b) they are processed to simple compounds by their own enzymes c) they remain quiescent until activation of G1-S Cdk d) they are consumed by macrophages e) they emerge in a parallel universe as components of anti-creatures

b) actin polymerization

What process provides the force that propels the leading edge of a motile cell forward? a) tubulin dimer polymerization b) actin polymerization c) myosin I motors d) myosin II motors e) dynein motors

a) catastrophic fraying of kinetochore microtubules

What provides the force that drives chromosomal segregation during anaphase A? a) catastrophic fraying of kinetochore microtubules b) GTP hydrolysis c) actin polymerization d) ATP hydrolysis

G-PROTEIN-COUPLED RECEPTORS Largest family of cell surface receptors ( > 700 different receptors)

What type of receptor is described? Transient activation of a "G protein", which usually signals through a membrane-associated enzyme & involves a significant amplification step

"Ionotropic Receptors" ION-CHANNEL-COUPLED RECEPTORS

What type of receptor is described? Transiently alter the ionic composition of the cytosol Change in membrane potential & Increase in cytosolic calcium

Bacteriorhodopsin

What utilizes a Photon-powered H+ Pump?

c) by promoting the transcription of Cdk inhibitors

When significant DNA damage is detected during G1 phase, PS3 is released from inhibition and arrests cell cycle at the Start checkpoint to prevent replication of damaged DNA. How does P53 prevent entry into S phase? a) by reactivating Rb protein b) by ubiquinating cyclin A c) by promoting the transcription of Cdk inhibitors d) by promoting anaphase promoting complex (APC) activity

b) Cyclic AMP response element binding (CREB) protein

When the cyclic AMP-dependent protein kinase (PKA) enters the nucleus, it phosphorylates which of the following transcription factors? a) CPK kinase (CBK2) b) Cyclic AMP response element binding (CREB) protein c) CREB binging protein (CBP) d) CREB protein kinase (CPK)

a) in the lamellapodium

Where in a motile cell would you expect to find most of the ARP complex? a) in the lamellapodium b) in the cortex of the cell c) at the trailing edge d) in the centrosome

INCORRECT c) G1-Cdk & cyclin C

Which of the following Cdk complex/ cyclin matches is INCORRECT? a) M-Cdk & cyclin B b) 5-Cdk & cyclin A c) G1-Cdk & cyclin C d) G1/S-Cdk & cyclin E

c) Gt

Which of the following G proteins plays a role in rhodopsin signaling in rod photoreceptors of vertebrates? a) Gi b) Go c) Gt d) Gq e) Gs

e) Gt

Which of the following G proteins signals through cGMP phosphodiesterase in retinal rod & cone cells? a) Gs b) Gi c) Go d) Gq e) Gt

d) keratins

Which of the following are intermediate filament proteins that are exclusively expressed in epithelial cells? a) nuclear lamins b) microfilaments c) neurofilaments d) keratins

a) nuclear lamins

Which of the following are intermediate filament proteins that are expressed in all eukaryotic cells? a) nuclear lamins b) keratins c) vimentin-related proteins d) neurofilaments

???? a or b

Which of the following best describes the apical-to-basolateral order of occurrence of cell-cell junctions in an epithelial cell? a) tight junctions - desmosomes - adherens junctions - gap junctions b) tight junctions - adherens junctions - desmosomes - gap junctions c) tight junctions - adherens junctions - gap junctions - hemidesmosomes d) adherens junctions - tight junctions - gap junctions - hemidesmosomes e) adherens junctions - tight junctions - desmosomes - gap junctions

b) cGMP levels decrease, Na+ channels close, the cell hyperpolarizes and glutamate release decreases

Which of the following best describes the events that occur after photoisomerization of 11-cis retinal in rod cells? a) cGMP levels increase, Na+ channels open, the cell depolarizes, and glutamate release increases b) cGMP levels decrease, Na• channels close, the cell hyperpolarizes and glutamate release decreases c) cGMP levels increase, Na+ channels close, the cell depolarizes, and glutamate release increases d) cGMP levels decrease, Na• channels close, the cell depolarizes, and glutamate release increases e) cGMP levels increase, Na+ channels close, the cell hyperpolarizes, and glutamate release decreases

c) nine sets of doublet microtubules surrounding two singlet microtubules

Which of the following best describes the microtubular structure of the axoneme of spermatozoa? a) nine sets of singlet microtubules surrounding two doublet microtubules b) nine sets of doublet microtubules surrounding one singlet microtubule c) nine sets of doublet microtubules surrounding two singlet microtubules d) nine sets of triplet microtubules surrounding one singlet microtubule e) nine sets of triplet microtubules surrounding two singlet microtubules

b) troponin complex

Which of the following binds calcium ions and promotes skeletal muscle contraction? a) tropomodulin b) troponin complex c) tropomyosin d) calmodulin e) contractin

d) adherens junctions

Which of the following cell-cell junctions is formed by cell adhesion molecules that are associated with actin filaments? a) desmosomes b) hemidesmosomes c) tight junctions d) adherens junctions e) gap junctions

c) tight junctions

Which of the following cell-cell junctions is responsible for preventing the diffusion of solutes between apical and basolateral extracellular compartments in epithelial tissues? a) desmosomes b) hemidesmosomes c) tight junctions d) adherens junctions e) gap junctions

d) phalloidin

Which of the following compounds binds to actin filaments and is frequently used to as an affinity reagent for fluorescent labeling of the act in cytoskeleton? a) colchicine b) cytochalasin c) taxol d) phalloidin e) vincristine

b) disintegration of the nuclear envelope

Which of the following events occurs during prometaphase? a) DNA replication b) disintegration of the nuclear envelope c) ubiquination of cyclin B d} inactivation of APC e) formation of the contractile ring

d) all of the above occur during prometaphase

Which of the following events occurs during prometaphase? a) breakdown of the nuclear envelope b) maturation of the spindle complex c) fixation of kinetochore microtubules d) all of the above occur during prometaphase e) none of the above occur during prometaphase

a) phosphorylation of ORC

Which of the following events prevents a second round of DNA replication a) phosphorylation of ORC b) phosphorylation of cdc25 c) ubiquination of cyclin B d) ubiquination of cdc6 e) none of the above

b) dissociation of Pi

Which of the following events triggers the "power stroke" for myosin II motor proteins? a) exchange of ADP for ATP b) dissociation of Pi c) ATP binding d) ATP hydrolysis

b) cohesin

Which of the following in NOT a substrate for M-Cdk complex? a) lamin B b) cohesin c) wee1 d) cdc25

c) α6β4

Which of the following integrin dimers is a component of hemidesmosomes? a) α2β1 b) α6β2 c) α6β4 d) α7β1 e) none of the above

d) nuclear lamins

Which of the following intermediate filaments is found in all animal cells? a) keratins b) vimentin c) neurofilaments d) nuclear lamins e) all of the above are found in all animal cells

a) keratins

Which of the following intermediate filaments is the cytoskeletal component of desmosomes between epithelial cells? a) keratins b) vimentin c) neurofilaments d) nuclear lamins e) none of the above

FALSE e) N and C terminal sequences are removed in the Golgi complex

Which of the following is FALSE regarding the extracellular matrix protein, Collagen? a) it is produced and tended by fibroblasts b) it is a triple coiled coil protein c) every third amino acid is glycine d) biosynthesis of collagen fibers requires ascorbic acid e) N and C terminal sequences are removed in the Golgi complex

b) centriole

Which of the following is NOT a microtubule organizing center (MOC)? a) centrosome b) centriole c) spindle pole d) basal body e) all of the above are MOCs

d) centriole is NOT

Which of the following is NOT a microtubule organizing center? a) centrosome b) spindle pole c) basal body d) centriole

b) vertebrate cilia is NOT

Which of the following is NOT an actin-rich structure? a) stress fibers b) vertebrate cilia c) the lamellipodium d) microvilli

c) neuronal axon is NOT

Which of the following is NOT composed of actin filaments? a) microvilli of epithelial cells b) contractile ring c) neuronal axon d) lamellipodia e) stress fibers

e) they hydrolyze ATP and move toward the minus(-) end of the microtubule

Which of the following is TRUE regarding dyne in motor proteins? a) they hydrolyze GTP and move toward the minus(-) end of the microtubule b) they hydrolyze GTP and move toward the plus(+) end of the microtubule c) they hydrolyze ATP and move toward the plus(+) end of the actin filament d) they hydrolyze ATP and move toward the plus(+) end of the microtubule e) they hydrolyze ATP and move toward the minus(-) end of the microtubule

b) they hydrolyze ATP and move toward the plus (+) end of the microtubule

Which of the following is TRUE regarding most kinesin motor proteins? a) they hydrolyze ATP and move toward the minus(-) end of the microtubule b) they hydrolyze ATP and move toward the plus (+) end of the microtubule c) they hydrolyze ATP and move toward the plus (+) end of the actin filament d) they hydrolyze GTP and move toward the plus (+) end of the microtubule e) they hydrolyze GTP and move toward the minus(-) end of the microtubule

a) laminin

Which of the following is a component of the basal lamina? a) laminin b) lamins c) prostacyclins d) fibronectin e) none of the above are components of the basal lamina

a) nuclear lamins

Which of the following is an intermediate filament that is found in ALL eukaryotic cells? a) nuclear lamins b) micro filaments c) keratins d) neurofilaments e) all of the above are intermediate filament proteins found in ALL eukaryotes

b) Cdc6

Which of the following is phosphorylated by S-Cdk to initiate DNA synthesis a) DNA polymerase b) Cdc6 c) MPF d) ORC e) Helicase

b) Cdc6

Which of the following is phosphorylated by S-Cdk to initiate DNA synthesis? a) DNA polymerase b) Cdc6 c) MPF d) ORC e) Helicase

c) nuclear lamin B

Which of the following is phosphorylated by the M-Cdk complex? a) p53 b) securin c) nuclear lamin B d) p21 e) all of the above are substrates for M-Cdk

c) Rb protein

Which of the following is the inhibitory binding partner for transcription factor E2F? a) cyclin D b) P53 c) Rb protein d) MAP kinase

d) hyaluronan

Which of the following is the largest glycosylaminoglycan (GAG)? a) chondroitin b) heparin c) dermatan d) hyaluronan e) all are approximately the same size

b) G1-S Cdk & cyclin E

Which of the following kinase-cyclin pairs is correctly matched? a) S Cdk & cyclin B b) G1-S Cdk & cyclin E c) M Cdk & cyclin C d) G1-Cdk & cyclin A e) All are correctly matched

c) G1 Cdk & cyclin C is INCORRECT

Which of the following kinase-cyclin pairs is incorrectly matched? a) S Cdk & cyclin A b) M Cdk & cyclin B c) G1 Cdk & cyclin C d) G1-S Cdk & cyclin E e) All are correctly matched

e) Wee1

Which of the following kinases is responsible for phosphorylation and inactivation of MCdk? a) MAP kinase b) Akt kinase c) S-Cdk d) Cyclin inactivating kinase e) Wee1

d) sarcoplasmic reticulum

Which of the following kinases is responsible for preventing the assembly of Ndc80 complexes on kinetochore microtubules? a) mitochondria b) T-tubules c) calcium ATPase d) sarcoplasmic reticulum

d) aurora-B kinase

Which of the following kinases is responsible for preventing the assembly of Ndc80 complexes on kinetochore microtubules? a) M-cdk complex b) MAP kinase c) polo kinase d) aurora-B kinase

c) kinesin 4, 10

Which of the following kinesin motor proteins binds directly to chromatin? a) kinesin 1 b) kinesin 13 c) kinesin 4, 10 d) kinesin 5

b) kinesin 13

Which of the following kinesins promotes catastrophic depolymerization of microtubules? a) kinesin 1 b) kinesin 13 c) kinesin 4/10 d) kinesin 5

d) Rho ie. Rho GTPase Family controls Actin Cytoskeleton ie. Striated muscle (Rhodamine-labeled phalloidin)

Which of the following monomeric G-proteins regulates the actin cytoskeleton? a) Rab b) Ras c) Ran d) Rho

a) dynein motors

Which of the following motor proteins is responsible for the wave-like movement of eukaryotic flagella? a) dynein motors b) myosin 2 motors c) Depends on the energy source d) kinesin 1 motors e) myosin 1 motors

b) M-Cdk complex

Which of the following phosphorylates and inactivates the Wee1 kinase at the onset of M-phase? a) p53 b) M-Cdk complex c) S-Cdk complex d) APC e) cdc25

d) formin dimers

Which of the following protein complexes can nucleate actin polymerization in the absence of existing actin filaments? a) fimbrin dimers b) filament dimers c) ARP complexes d) formin dimers

a) formin dimers

Which of the following protein complexes is capable of nucleating actin filaments? a) formin dimers c) centrioles b) gamma tubulin ring complexes d) cofilin e) none are capable of nucleating actin filaments

a) ARP complexes

Which of the following protein complexes is responsible for the nucleation of actin polymerization at the leading edge of motile cells? a) ARP complexes b) Akt complexes c) Bax complexes d) APC complexes e) none of the above

c) JAKs

Which of the following protein kinases phosphorylates members of the STAT family of signaling molecules? a) none of the above kinases phosphorylate STATs b) cyclic AMP dependent protein kinases c) JAKs d) MAP kinases e) CAM kinases

c) tau

Which of the following proteins determines the packing density of microtubules in axons? a) XMAP 215 b) kinesin 13 c) tau d) plectin

a) cdh1

Which of the following proteins is required to sustain G1 phase? a) cdh1 b) p53 c) cdc25 d) mTOR e) myc

a) wee1

Which of the following proteins is responsible for phosphorylation and inactivation of M-cdk? a) wee1 b) cdc20 c) CAK d) cdc25

c) troponin --> Calcium attaches to troponin/ tropomyosin; they roll away, exposing the active site on actin. Calcium permits muscle contraction by interacting with troponin • Tropomyosin masks myosin binding sites on actin filaments • Binding of calcium to troponin complex causes conformation change that moves tropomyosin, revealing myosin binding sites & initiating contraction Myosin cross-bridges attach to active site on actin. After attachment, the cross-bridges pivot, pulling the thin filaments.

Which of the following proteins is the calcium sensor that triggers contraction in the sarcomere? a) trampolinin b) tropomyosin c) troponin d) tropomodulin

d) cofilin

Which of the following proteins promotes the depolymerization of actin filaments near the lamellipodium of a motile cell? a) severin b) fimbrin c) ARP d) cofilin

c) a calcium-gated calcium channel

Which of the following proteins releases calcium from the sarcoplasmic reticulum in response to muscle depolarization? a) the nicotinic cholinergic receptor b) a voltage-gated calcium channel c) a calcium-gated calcium channel d) an M-type calcium ATPase e) a sodium-calcium antiporter

a) cdh1

Which of the following proteins replaces cdc20 to maintain anaphase promoting complex (APC) activity during G1 phase? a) cdh1 b) cdc6 c) Rb d) cdc25

b) tropomodulin

Which of the following proteins serves as the minus(-) end actin capping protein in the sarcomere? a) tropomyosin b) tropomodulin c) CapZ d) troponin

d) capZ

Which of the following proteins serves as the plus(+) end capping protein of actin filaments in the sarcomere? a) tropomodulin b) troponin C c) tropomyosin d) capZ

b) cofilin

Which of the following proteins severs (breaks} actin filaments in the lamellapodium? a) profilin b) cofilin c) deformin d) formin

d} condensin

Which of the following refers to the SMC protein complex that gathers and organizes newly replicated DNA into chromosomes ? a) gatherin b) compactin c) cohesin d} condensin e) compressin

d) cdc25

Which of the following refers to the phosphatase that activates M-Cdk to initiate M-phase? a) phosphatase B b) M phosphatase c) cdc15 d) cdc25 e) none of the above

e) cdc25

Which of the following refers to the phosphatase that activates M-Cdk to initiate M-phase? a) phosphatase B b) M phosphatase c) cdc6 d) cdc20 e) cdc25

b) condensin

Which of the following refers to the protein complex that gathers and organizes newly replicated DNA into chromosomes? a) gatherin b) condensin c) cohesin d) compressin e) chromatin

e) cohesins

Which of the following refers to the proteins that are cleaved by separase to release sister chromatids at anaphase? a) anaphase promoting complex (APC) b) cyclin B c) condensins d) separins e) cohesins

a) tropomodulin

Which of the following serves as the minus(-) end capping protein of actin filaments in striated muscle? a) tropomodulin b) troponin c) tropomyosin d) CapZ e) none of the above

d) CapZ

Which of the following serves as the plus (+) end capping protein of actin filaments in sarcomeres? a) tropomyosin b) troponin c) tropomodulin d) CapZ e) none of the above

c) Ras

Which of the following small GTPases plays a key role in the mitogen activated protein (MAP) kinase pathway? a) Rab b) Rae c) Ras d) Raf e) Ran

d) They are only found in soft-bodied organisms is FALSE

Which of the following statements about microtubules is FALSE? a) Most are composed of 13 protofilaments b) They polymerize at the plus (+) end c) They are polymers of alpha-beta tubulin dimers d) They are only found in soft-bodied organisms

b) microtubules grow fastest from the minus(-) end

Which of the following statements is FALSE regarding microtubules? a) microtubules are composed of 13 "protofilaments" b) microtubules grow fastest from the minus(-) end c) microtubules display the property of dynamic instability d) microtubules undergo "catastrophe", during which they fray at the plus(+) end e) all of the above are TRUE regarding microtubules

a) microtubules grow fastest from the minus (-) end is FALSE

Which of the following statements is FALSE regarding microtubules? a) microtubules grow fastest from the minus (-) end b) microtubules are composed of 13 "protofilaments" c) microtubules undergo "catastrophe", during which they fray at the plus(+) end d) microtubules are often stabilized by plus end capping proteins e) all of the above are TRUE regarding microtubules

d) They hydrolyze ATP and move toward the plus (+) end of microtubules.

Which of the following statements is TRUE regarding most kinesin motor proteins? a) They hydrolyze ATP and move toward the minus (-) end of microtubules. b) They hydrolyze GTP and move toward the minus (-) end of microtubules. c) They hydrolyze GTP and move toward the plus (+) end of microtubules. d) They hydrolyze ATP and move toward the plus (+) end of microtubules.

a) They hydrolyze ATP and move toward the minus(-) end of microtubules.

Which of the following statements regarding cytoplasmic dyneins is TRUE? a) They hydrolyze ATP and move toward the minus(-) end of microtubules. b) They hydrolyze GTP and move toward the minus(-) end of microtubules. c) They hydrolyze GTP and move toward the plus(+) end of microtubules. e) They hydrolyze ATP and move toward the plus{+) end of microtubules.

c) cilia

Which of the following structures is NOT supported by the actin cytoskeleton? a) cont ractile bundle b) lamelhpodium c) cilia d) microvilli

a) phosphatidylinositol 4,5-bisphosphate

Which of the following substrates is phosphorylated by the Pl3 kinase? a) phosphatidylinositol 4,5-bisphosphate b) phosphatidylinositol 3,5-bisphosphate c) phosphatidylinositol 3,4-bisphosphate d) phosphatidylinositol 3,4,5-trisphosphate

a) actin polymerization

Which process provides the force that propels the leading edge of a motile cell forward? a) actin polymerization b) microtubule polymerization c) myosin I motor activity d) myosin II motor activity e) kinesin motor activity

b) Rac

Which small GTPase is often activated during remodeling of the actin cytoskeleton? a) Rap b) Rac c) Rab d) Ran e) Ras

b) Rac

Which small GTPase might be activated during remodeling of the actin cytoskeleton? a) Rab b) Rac c) Ran d) Ram e) dynamin

d) CyclinA

You have isolated a temperature sensitive yeast mutant. When maintained at the restrictive temperature, all of the yeast cells are arrested at the "start" checkpoint (G1-S transition) due to a loss-of-function mutation of a single gene. Below are listed five proteins. Which one is most likely to be the protein responsible for the observed phenotype (i.e., arrest at G1-S transition)? a) PS3 b) RB c) P21 d) CyclinA e) Cyclin B

c) APC/C

You have isolated a temperature sensitive yeast mutant. When maintained at the restrictive temperature, all of the yeast cells are arrested at the Metaphase-Anaphase (M-A) checkpoint due to a loss-of-function mutation of a single gene. Which of the following proteins / protein complexes is most likely responsible for the observed phenotype (i.e., arrest at M-A checkpoint)? a) P53 b) cyclin D c) APC/C d) cyclin A

actin filiments

_______ are 7 nm in diameter & dynamic

Microtubules

_________ are 25 nm in diameter & dynamic

Target Protein which is activated by the ALPHA subunit HYDROLYSIS OF GTP BY THE a SUBUNIT INACTIVATES THIS SUBUNIT AND CAUSES IT TO DISSOCIATE FROM THE TARGET PROTEIN then INACTIVE a SUBUNIT REASSEMBLES WITH bg COMPLEX TO RE-FORM AN INACTIVE G PROTEIN

__________ protein acts as a GAP

Keratins (cytoplasmic) ie. intermediate filaments (10 nm in diameter & stable)

__________ transmit / distribute mechanical stress between adjacent epithelial cells through "Desmosome" Junctions ie. Epidermolysis Bullosa

Pertussis Toxin Gi (alpha) ie. w/ ADPR

__________Toxin: Inhibit Exchange Locked "OFF" & UP cAMP

Cholera Toxin Gs (alpha) ie. w/ ADPR

__________Toxin: Inhibit GTPase Locked "ON" & UP cAMP

Cyclic AMP (cAMP)

___________ is the original "second messenger" characterized by Sutherland & Rall (1968)

Olfactory These proteins are concentrated in modified cilia that project from olfactory neurons. Each neuron is specialized to detect a single odorant molecule

___________ receptors are GPCRs that signal through Golf , a close cousin of Gs

Opsin ie. Cell Signal Cascade in the Retina

____________ activates Gt which activates the enzyme, cGMP PDE (phosphodiesterase). Then the Enzyme degrades cGMP & Na+ channels close

5'-AMP

_____________ also appears to function as a chemical messenger in some systems

Delta - Notch --> cleaved Notch tail migrates to nucleus

_____________ interaction causes the proteolytic liberation of the cytosolic domain of Notch, which binds to DNA and recruits transcription factors

Phosphotyrosine ie. ENZYME-COUPLED RECEPTORS

______________ residues serve as binding sites for recruitment of other signaling proteins

Growth factors ie. mTOR phosphorylates proteins that regulate protein synthesis, cell proliferation, cell motility, transcription, etc...

___________________ also signal through RTKs - PI-3 - Akt pathway to promote protein synthesis & reduce protein turnover, resulting in growth. ie. the mTOR protein is an important downstream serine-threonine kinase in the Akt pathway.

Intermediate filaments

__________are 10 nm in diameter & stable

protein kinase A (PKA) "Activation of cAMP-dependent protein kinase (PKA)"

cAMP activates _________ ie. one complex + two kinases creates a "kinase cascade" which results in Glycogen Breakdown

second messengers

in Metabotropic Receptors: __________ are SMALL MESSENGER MOLECULES DIFFUSE TO ACT ON INTRACELLULAR SIGNALING PROTEINS

mTOR = (mammalian Target Of Rapamycin) The mTOR protein is an important downstream serine-threonine kinase in the Akt pathway. mTOR phosphorylates proteins that regulate protein synthesis, cell proliferation, cell motility, transcription, ...etc.

mTOR