Home > 38 Membrane Receptors and Signal Transduction > RECEPTOR COUPLING TO INTRACELLULAR SIGNAL TRANSDUCTION

RECEPTOR COUPLING TO INTRACELLULAR SIGNAL TRANSDUCTION Body_ID: HC038013 Some sensory systems use receptor-coupled signaling Body_ID: HC038016 page 542 page 543 Body_ID: P0543 Body_ID: T038001 Table 38-1. Classification of membrane receptors. Body_ID: None Membrane receptors Body_ID: T038001.50 Receptor class Transmembrane-spanning domains Intrinsic catalytic activity Accessory coupling/regulatory molecules Examples of receptor subclasses Body_ID: T038001.100 G-protein-coupled receptors (serpentine receptors) multipass (seven transmembrane α-helices) none G-proteins β-adrenergicα-adrenergicmuscarinicchemokines (IL-8)rhodopsin (vision) Body_ID: T038001.150 Ion-channel receptors(ligand-gated receptors) multipass; generallyform multimeric complexes none none neurotransmittersionsnucleotidesinositol trisphosphate (IP3) Body_ID: T038001.200 Intrinsic receptortyrosine kinases single-pass transmembranedomain, but may be multimeric(e.g. insulin receptor) tyrosine kinase none epidermal growth factor (EGF)nerve growth factor (NGF)platelet-derived growth factor (PDGF)fibroblast growth factor (FGF)insulin Body_ID: T038001.250 Tyrosine kinase-associated receptors single-pass transmembranedomain, but generally formmultimeric receptors none some requireITAM/ITIM-containingproteins antigen receptors(ITAM-Src-related kinases)FcyR (ITIM-Src-related kinases)hemopoietin cytokine receptors(Janus kinases) Body_ID: T038001.300 Intrinsic tyrosinephosphatase receptors single-passtransmembranedomain tyrosinephosphatase none CD45-phosphatase receptor Body_ID: T038001.350 Intrinsic serine-threoninereceptor kinases single-passtransmembranedomain serine-threoninekinase none tumor growth factor β (TGF-β) Body_ID: T038001.400 Intrinsic guanylatecyclase receptors single-passtransmembranedomain guanylate cyclase(generates cGMP) none atrial natriuretic peptide (ANP) receptors Body_ID: T038001.450 Death-domain receptors single-passtransmembranedomain none death-domain accessoryproteins (TRADD, FADD,RIP, TRAFs) tumor necrosis factor (TNF-α)Fas Body_ID: T038001.500 Body_ID: T038001.550 Body_ID: T038001 cGMP, cyclic guanosine monophosphate; FADD, fas-associated death domain; FcγR, Fc-γreceptor (receptor for immunoglobulin G); IL, interleukin; ITAM/ITIM, immunoreceptor tyrosine activation/inhibition motif; RIP, receptor-interacting protein; Src, Src-tyrosine kinase; TRADD, TNF-receptor-associated death domain; TRAFs, TNF-receptor-associated factors. Body_ID: None In addition to hormone receptors, sensory systems such as vision (Chapter 39, Fig. 39.4), taste and smell use similar mechanisms of cell-surface membrane receptor-coupled signal transduction (see Table 38.1). Some of these receptors, for example the β-adrenergic receptors (see Fig. 38.2) or the antigen receptors on lymphocytes, have no intrinsic catalytic activity and serve simply as specific recognition units. These receptors use a variety of mechanisms, including adaptor molecules or catalytically active regulatory molecules such as G-proteins (guanosine triphosphatases, GTPases, which hydrolyze GTP), to couple them to their effector signaling elements, which are generally enzymes (often called signaling enzymes or signal transducers) or ion channels (Fig. 38.3). In contrast, other receptors - such as the intrinsic tyrosine kinase receptors for growth factors (e.g. platelet-derived growth factor, PDGF) or the intrinsic serine kinase receptors for molecules like transforming growth factor-β (TGF-β) - have extracellular ligand-binding domains and cytoplasmic catalytic domains. Thus, after receptor-ligand interactions (receptor ligation), these receptors can directly initiate their signaling cascades by phosphorylating and modulating the activities of target signal-transducing molecules (downstream signaling enzymes). These in turn propagate the growth factor signal by modulating the activity of further specific signal transducers or transcription factors, leading to gene induction (see Chapter 41). Body_ID: P038010 Integration link: Developmental signalling pathways - sonic hedgehog Taken from Human Embryology & Developmental Biology 3E pages 542 - 543 Copyright © 2007 Elsevier Inc. All rights reserved. Read our Terms and Conditions of Use and our Privacy Policy. For problems or suggestions concerning this service, please contact: studentconsult.help@elsevier.com