Ch 16 - Cell Signaling Flashcards
adaptation
adjustment of sensitivity following repeated stimulation; allows a cell or organism to register small changes in a signal despite a high background level of stimulation
adenylyl cyclase
enzyme that catalyzes the formation of cyclic AMP from ATP; an important component in some intracellular signaling pathways
Ca2+/calmodulin-dependent protein kinase (CaM-kinase)
enzyme that phosphorylates target proteins in response to an increase in Ca2+ ion concentration through its interaction with the Ca2+ binding protein calmodulin
calmodulin
small Ca2+-binding protein that modifies the activity of many target proteins in response to changes in Ca2+ concentration
cell signaling
the molecular mechanisms by which cells detect and respond to external stimuli and send messages to other cells
cyclic AMP
small intracellular signaling molecule generated from ATP in response to hormonal stimulation of cell-surface receptors
cyclic-AMP-dependent-protein-kinase (PKA)
enzyme that phosphorylates target proteins in response to a rise in intracellular cyclic AMP concentration
diacylglycerol (DAG)
small messenger molecule produced by the cleavage of membrane inositol phospholipids in response to extracellular signals. helps activate protein kinase C
enzyme-coupled-receptor
transmembrane protein that, when stimulated by the binding of a ligand, activates an intracellular enzyme (either a separate enzyme or part of the receptor itself)
extracellular signal molecule
any molecule present outside the cell that can elicit a response inside the cell when the molecule binds to a receptor
G protein
a membrane-bound GTP-binding protein involved in intracellular signaling; composed of three subunits, this intermediary is usually activated by the binding of a hormone or other ligand to a transmembrane receptor
G-protein-coupled receptor (GPCR)
Cell-surface receptor that associates with an intracellular trimeric GTP-binding protein (G protein) after activation by an extracellular ligand. these receptors are embedded in the membrane by seven transmembrane α helices
GTP-binding protein
intracellular signaling protein whose activity is determined by its association with either GTP or GDP. includes both trimeric G proteins and monomeric GTPases, such as Ras
hormone
extracellular signaling molecule that is secreted and transported via the bloodstream (in animals) or the sap (in plants) to target issues on which it exerts a specific effect
inositol 1,4,5-triphosphate (IP3)
small intracellular signaling molecule that triggers the release of Ca2+ from the endoplasmic reticulum into the cytosol; produced when a signal molecule activates a membrane-bound protein called phospholipase C.