Lesson 6

endocrine signaling

usually a long distance between signaling cell and target cells secreted signaling cells travel throughout the body where appropriate slower but longer lasting response

phosphotase

any of a number of enzymes that removes a phosphate group from a protein, reversing the action of a kinase

G protein-coupled receptors(GPCR)

A receptor that acts through a heterotrimeric (3 component) G protein to activate effector proteins. the effector proteins then function as enzymes to produce second messengers such as cAMP or IP3

autophosphorylation

Autophosphorylation is a type of post-translational modification of proteins. It is generally defined as the phosphorylation of the kinase by itself. In eukaryotes, this process occurs by the addition of a phosphate group to serine, threonine or tyrosine residues within protein kinases, normally to regulate the catalytic activity.

Choose the statement which is NOT true: Signaling occurs within multicellular organisms and between single-cell organisms Cells use receptor proteins to detect signals Cells respond to all signal molecules (ligands) that they come in contact with Extracellular signals are converted into intracellular signals (signal transduction)

Cells respond to all signal molecules (ligands) that they come in contact with

Which would be the correct sequence of events for a G-Coupled Protein Receptor (GPCR) signal transduction pathway? Ligand binds to GCPR - Receptor; G-Protein; effector protein; cellular response Ligand binds to GProtein; activates receptor; effector protein; cellular response Ligand binds to effector protein; activates G protein; cellular response. Ligand binds to GCPR - "deactivation" of G protein; G protein subunit deactivates effector protein; cellular response

Ligand binds to GCPR - Receptor; G-Protein; effector protein; cellular response

PIP2

Phosphatidylinositol 4,5-bisphosphate or PtdIns(4,5)P2, also known simply as PIP2, is a minor phospholipid component of cell membranes. PtdIns(4,5)P2 is enriched at the plasma membrane where it is a substrate for a number of important signaling proteins.

Which is NOT true of phosphorylation? Kinase uses ATP to add a phosphate to select amino acids RTK's operate by autophosphorylation, which then leads to a cellular response Phosphorylation will always turn the "target" protein on; dephosphorylation will always turn the "target" protein off. Kinase cascades can amplify signals in the cell

Phosphorylation will always turn the "target" protein on; dephosphorylation will always turn the "target" protein off.

Ras

Ras is a family of related proteins which is expressed in all animal cell lineages and organs. All Ras protein family members belong to a class of protein called small GTPase, and are involved in transmitting signals within cells (cellular signal transduction).

Choose the cell to cell signaling mechanism that best represents how our nervous system operates: Direct contact Paracrine signaling Endocrine signaling Synaptic signaling

Synaptic signaling

second messenger

The term second messenger was coined upon the discovery of these substances in order to distinguish them from hormones and other molecules that function outside the cell as "first messengers" in the transmission of biological information.

signal amplification

The use of specific detection methodologies to directly increase the signal in proportion to the amount of target in the reaction. Examples include the use of branched DNA probes that contain a reporter group or enzyme amplification.

MAP kinase

any of a class of protein kinases that activiate transcription factors to alter gene expression. a mitogen is any molecule that stimulates cell division. MAP kinases are activated by kinase cascades

Adaptor proteins

any of a class of proteins that acts as a link between a receptor and other proteins to initiate cell transduction

adenylyl cyclase is activated by calcium cAMP a G protein protein kinase A

a G protein

cell surface receptors

a cell surface protein that binds a single molecule and converts the extracellular signal into an intracellular one

receptor tyrosine kinase (RTK)

a diverse group of membrane rececptors that when activated have kinase enzymatic activity. specifically, they phosphorylate proteins on tyrosine. their activiation can lead to diverse cellular responses

cAMP

a form of adenosine monophosphate (AMP) in which the atoms of the phosphate group form a ring; found in almost all organisms, cAMP functions as an intracellular second messenger that regulates a diverse array of metabolic activities

.calmodulin

a protein that binds calcium and is involved in regulating a variety of activities in cells.

diaclyglycerol (DAG)

a second messenger that is released, along with ip3, when phospholipase C cleaves PIP2. DAG can have a variety of cellular effects through activation of protein kinases

ligand

a signaling molecule that binds to a specific receptor protein, initiating signal transduction in cells

paracrine signaling

a type of chemical signaling between cells in which the effects are local and short lived

phosphorylation

chemical rxn resulting in the addition of a phosphate group to an organic molecule. phosphorylation of ADP yields ATP. many proteins are also activated or inactivated by phosphorylation

TF: endrocrine signaling is typically faster than paracrine signaling

false

TF: every cell in your body can respond to every signal molecule in your body

false

TF: phosphorylation of an enzyme will always increase the activity of that enzyme

false

kinase

kinase is an enzyme that catalyzes the transfer of phosphate groups from high-energy, phosphate-donating molecules to specific substrates.

A researcher is trying to produce a new cancer drug to be tested on small tumors. The tumor has to be localized in a small area of the body and cannot have metastasized (spread to other areas of the body). Furthermore, this drug must prohibit the signaling from one tumor cell to another tumor cell. Given the above information, this new drug will prohibit autocrine signaling between tumor cells. endocrine signalizing between tumor cells. direct physical contact between tumor cells. paracrine signaling between tumor cells.

paracrine signaling between tumor cells.

A mutation that inactivates a ____ may prevent a signal pathway from being turned off second messenger G protein receptor protein phosphotase

phosphotase

IP3 (inositol triphosphate)

second messenger produced by the cleavage of phosphatidylinositol biophosphate

effector

used to describe an organ, a gland, or a muscle that responds to a nerve impulse.

signal transduction

the events that occur within a cell on receipt of a signal sequence of polypeptide, and then docks with a receptor that forms a channel in the ER membrane. in this way the polypeptide is released into the lumen of the ER

dephosphorylation

the removal of a phosphate group, usually by a phosphatase enzyme. many proteins can be activated or inactivated by dephosphorylation

direct contact signaling

touching, fastest, gap junctions creates pores in the membranes of adjacent cells