cell signalling definitions Flashcards
(30 cards)
receptor tyrosine kinase (RTK)
Cell-surface receptor with an extracellular ligand-binding domain and an intracellular kinase domain that phosphorylates signaling proteins on tyrosine residues in response to ligand binding.
enzyme-coupled receptor
A major type of cell-surface receptor that has a cytoplasmic domain that either has enzymatic activity or is associated with an intracellular enzyme. In either case, the enzymatic activity is stimulated by an extracellular ligand binding to the receptor.
SH2 domain
Src homology region 2, a protein domain present in many signaling proteins. Binds a short amino acid sequence containing a phosphotyrosine.
Ras superfamily
Large superfamily of monomeric GTPases (also called small GTP-binding proteins) of which Ras is the prototypical member.
Ras
A small family of proto-oncogenes that are frequently mutated in cancers, each of which produces a Ras monomeric GTPase.
Ras GEFs
Ras guanine nucleotide exchange factors; stimulate the dissociation of GDP and the subsequent uptake of GTP from the cytosol, thereby activating Ras.
Ras GAPs
Ras GTPase-activating proteins; increase the rate of hydrolysis of bound GTP by Ras, thereby inactivating Ras.
MAP kinase module (mitogen-activated protein kinase module)
An intracellular signaling module composed of three protein kinases, acting in sequence, with MAP kinase as the third. Typically activated by a Ras protein in response to extracellular signals.
Ras–MAP-kinase signaling pathway
Intracellular signaling pathway that relays signals from activated receptor tyrosine kinases to effector proteins in the cell, including transcription regulators in the nucleus.
tyrosine-kinase-associated receptor
Cell-surface receptor that functions similarly to receptor tyrosine kinases (RTKs), except that the kinase domain is encoded by a separate gene and is noncovalently associated with the receptor polypeptide chain.
receptor tyrosine kinase (RTK)
Cell-surface receptor with an extracellular ligand-binding domain and an intracellular kinase domain that phosphorylates signaling proteins on tyrosine residues in response to ligand binding.
G-protein-coupled receptor (GPCR)
A seven-pass cell-surface receptor that, when activated by its extracellular ligand, activates a G protein, which in turn activates either an enzyme or ion channel in the plasma membrane.
regulator of G protein signaling (RGS)
A type of GAP protein that binds to a trimeric G protein and enhances its GTPase activity, thus helping to limit G-protein-mediated signaling.
cyclic AMP (cAMP)
Nucleotide that is generated from ATP by adenylyl cyclase in response to various extracellular signals. It acts as a small intracellular signaling molecule, mainly by activating cAMP-dependent protein kinase (PKA). It is hydrolyzed to AMP by a phosphodiesterase.
adenylyl cyclase (adenylate cyclase)
Membrane-bound enzyme that catalyzes the formation of cyclic AMP from ATP. An important component of some intracellular signaling pathways.
cyclic AMP phosphodiesterase
Specific enzyme that rapidly and continually destroys cyclic AMP, forming 5′-AMP.
cyclic-AMP-dependent protein kinase
Enzyme that phosphorylates target proteins in response to a rise in intracellular cyclic AMP.
CRE-binding (CREB) protein
Transcription regulator that recognizes the cyclic AMP response element (CRE) in the regulatory region of genes activated by cAMP. On activation by PKA, phosphorylated CREB recruits a transcriptional coactivator (CREB-binding protein; CBP) to stimulate transcription of target genes.
phospholipase C (PLC)
Membrane-bound enzyme that cleaves inositol phospholipids to produce IP3 and diacylglycerol in the inositol phospholipid signaling pathway. PLCβ is activated by GPCRs via specific G proteins, while PLCγ is activated by RTKs.
phosphatidylinositol 4,5-bisphosphate [PI (4,5)P2, PIP2]
Membrane inositol phospholipid (a phosphoinositide) that is cleaved by phospholipase C into IP3 and diacylglycerol at the beginning of the inositol phospholipid signaling pathway. It can also be phosphorylated by PI 3-kinase to produce PIP3 docking sites for signaling proteins in the PI-3-kinase–Akt signaling pathway.
inositol 1,4,5-trisphosphate (IP3)
Small intracellular signaling molecule produced during activation of the inositol phospholipid signaling pathway. Acts to release Ca2+ from the endoplasmic reticulum.
diacylglycerol (DAG)
Lipid produced by the cleavage of inositol phospholipids in response to extracellular signals. Composed of two fatty acid chains linked to glycerol, it serves as a small signaling molecule to help activate protein kinase C (PKC).
protein kinase C (PKC)
Ca2+-dependent protein kinase that, when activated by diacylglycerol and an increase in the concentration of cytosolic Ca2+, phosphorylates target proteins on specific serine and threonine residues.
calmodulin
Ubiquitous intracellular Ca2+-binding protein that undergoes a large conformation change when it binds Ca2+, allowing it to regulate the activity of many target proteins. In its activated (Ca2+-bound) form, it is called Ca2+/calmodulin.
