Transmembrane Signaling Protocols

Abstract

G-protein receptors GPCRs) make up the largest and most diverse family of membrane receptors in the human genome, relaying information about the presence of diverse extracellular stimuli to the cell interior.All known GPCRs share a common architecture of seven membrane-spanning helice connected by intra-and extracellular loops.Most GPCR-mediated cellular responses result form acting as a lingand-activated guanine nucleotide exchange factor for heterotrimeric guanine nucleitode-binding (G) proteins whose dissociated subunits activate effector enzymes or ion channels.GPCR signalling is a subject to extensive negative regulation through rreceptor desensitiization, sequestration, and down regulation, terminatin of G protein activation by GTPase-activation proteins, and enzymatic degradation of second messengers.