cell bio ch 16
Ras Protein
- loses Kinase each step -mitogen: chemical substance that triggers mitosis -target of cancer (conti. mitosis)
what makes a response fast or slow?
- multiple steps vs one step -channels increase response time -intracellular receptors
what happens during G-protein receptors
-7 transmembrane helas -subunits (alpha/beta/Gamma) -GTP binding (activation enzyme)
What are the main parts of protein phosphorylation?
-ATP signal on (protein kinase) -ADP signal off (protein phosphatase)
Cyclic AMP signaling pathway
-ATP to (adenylyl cyclase) Cyclic AMP to (phosphodiesterase) AMP -caffeine inhibits phosphodiesterase
what happens when dissolved gases are a signal
- they move across plasma membrane activating NO synthase (NOS) -rapid diffusion of NO across membrane binding to guanylyl cylase - GTP to cylic GMP relaxing smooth muscle cell
BAD
-(Apoptosis) bound to Bd2 (active) -Akt removes (activates) Bd2 inactivating signal
In the pathway through which nitric oxide (NO) triggers smooth muscle relaxation in blood-vessel wall. what situations would lead to relaxation of smooth muscle cell in absence of acetylcholine?
- a muscle cell that has a defect in guanylyl cyclase such that it constitutively converts GTP to cyclic GMP
Survival signal within a cell
- activates PI-3 Kinase -phosphorylate inositol phospholipid -Akt (PKB) docks after protein kinase before protein kinase
G-protein activation with enzyme
- alpha activation activates enzyme which activates second massagers
what happens when some bacterial toxians enter?
-Activity of G-protein is altered -hijack signaling (unable to turn on or off) -Cholera: doesn't hydrolyze GTP/ violent dierria/dehydration
What are the main parts of GTP-binding proteins?
-GTP binds (on) -GTP hydrolyzed (off) -hydrolyzed on own (GAP)/ binding (GEF)
adrenocorticotropic hormone ACTH
-Target tissue: adrenal gland -major response: cortisol secretion
thrombin (proteolytic enzyme)
-Target tissue: blood platelets -Major response: aggregation
vasopressin (peptide hormone)
-Target tissue: liver -Major response: glycogen breakdown
acetylcholine
-Target tissue: pancreas/skeletal muscle -Major response: secretion of amylase (digestive enzyme)/contraction
Ca+2 in G proteins
-activate ion channels/ PKC/ Calmogoin (enzyme) -DAG (diacylglycerol) activates PKC -more rapid due to channels
What is an effector protein?
-activates protein within cell to create response -some direct effect on target cells
contact-dependent
-almost touching (most intimate) -no signal sent -signal embedded in membrane to be up taken from other cells -Fruit fly: Exhibit signal (Delta) to be taken by receptor (notch) tells nearby cells to inhibit signal
what's a positive feedback regulation?
-component enhances response
what is the process of a cortisol signal?
-conformational change activates receptor protein -activated receptor-cortisol complex moves into nucleus -activated receptor-cortisol complex binds to regulatory region of target gene/ activates transcription of target gene
the local mediator nitric oxide stimulates intracellular enzyme guanylyl cylase by ___.
-diffusing into cell stimulating directly
RTK and GTPase Ras (enzyme-coupled receptors)
-hydrolyzed GTP (Ras) doesn't need assistance -target of cancer (signal doesn't stop)
what's negative feedback regulation?
-inhibits/lowers signal response
neuronal signaling
-longer distant to specific location -down axon to synapse to target cells receptors -chemical signal to electrical signal
RTKs recruit complex (enzyme-coupled receptors)
-needs to be Dimer to be active (inactive=close) -active dimerization (transphorlating of surrounding P)
what do intracellular signal pathways do?
-relay signal onwards/amplifies signal received/makes stronger -integrates multiple signals into one to be amplified
Calcium in egg cells
-rushes in locking the bound sperm and inhibiting other sperm -intracellular development
what happens during a Ion-channel-coupled receptors
-signal binds to channel and opens channel -producing electrical current
what's intracellular Signaling?
-signal from cell receptor generally communicated into cell interior
paracrine signaling
-stays in extracellular fluid to bind to neighboring/ nearby cells
What are the 4 types of signals?
-survival (normal) -grow/divide -differentiate -die
Adrenaline, glucagon
-target tissue: fat -major response: fat breakdown
Adrenaline
-target tissue: heart -Major response: increase HR/ force of contraction
Adrenaline
-target tissue: skeletal muscle -major response: glycogen breakdown
endocrine signals
-travels farther than any other signal -goes into bloodstream until reaches receptor -hormone sends signal message throughout body
G-protein coupled receptors
-trimetric (alpha, beta, gamma) -Receptor protein (alpha) changes to interact with G protein (beta, gamma)/bind with GTP -activation of effector protein/ separation of alpha from beta/gamma unit
what does phosphodesterace do to NO cycle?
-turns off cycle keeps cylic GMP active -Constance relaxation state
Regulation of Ion-channels from G-proteins
-upon separation/ Alpha activation the beta/gamma binds to channel
extracellular signal
-water-soluble= through receptor -target molecule responds to intracellular
what happens during Enzyme-coupled receptors
-when activated activates enzyme (catalytic domain) -variety of pathways activated
autocrine signaling
-when released binds with itself
Rank (contact-dependent, endocrine signaling, paracrine signaling, neuronal signaling) in order of distance. 1 being shortest and 4 being longest
1 contact dependent 2 paracrine signaling 3 neuronal signaling 4 endocrine signaling
T/F Phosphatases remove phosphate from GTP-bind proteins, turning off
False
knowing about the cell membrane, which signal molecules would you expect to rely on cell surface receptor proteins to initiate intracellular signaling?
Large, hydrophilic
what could you hypothesize about amino acids of GPCR which cross plasma membrane?
amphipathic (hydrophilic outside/hydrophobic inside)
During nervous-system development in Drosophila, membrane-bound protein Delta acts as inhibitory signal to prevent neighboring cells from developing into neuronal cells. Delta is involved in ___ signaling.
contact-dependent
T/F extracellular signal molecules that are hydrophilic must bind to a cell-surface receptor so as to signal a target cell to change its behavior
true
T/F PI 3-kinase phosphorylates a lipid in the plasma membrane.
true
T/F The regulation of inflammatory responses at the site of an infection is an example of paracrine signaling.
true
