国外大学细胞生物学课件 英文课件16.ppt

Page 1 D103 - Cell Biology Lecture 16 - Trimeric G-protein coupled receptors ? 2011 Grant MacGregor & Christine S ü tterlin All rights reserved a seven ?-helix ‘ serpentine ’ transmembrane receptor a hetero-trimeric G -protein mended Reading: MBOC 5e, pages 904 - 921 Lecture 16 – Signaling III - G-Protein coupled receptors Page 2 D103 - Cell Biology Lecture 16 - Trimeric G-protein coupled receptors ? 2011 Grant MacGregor & Christine S ü tterlin All rights reserved ? Large family of related proteins. ? Evolved from a common ancestor by gene duplication and divergence. ? These proteins bind and hydrolyze GTP. While hydrolyzing GTP, these proteins convey a signal to ponents of the intracellular signaling apparatus. ? GTPases participate in many cellular activities : - Membrane traffic , . Arf, Rab , Sar; monomeric GTPase - Nuclear transport , . Ran; monomeric GTPase - Regulation of the cytoskeleton , . Rho; monomeric GTPase - Protein synthesis , . EF-Tu ; monomeric GTPase - Proteintranslocation in ER , . SRP; monomeric GTPase - Signal transduction , . Ras , monomeric GTPase - Signal transduction , . G ??? plus ???????, heterotrimeric GTPase The Family of GTP-binding proteins (aka GTPases or G-proteins) - what do they do ? Page 3 D103 - Cell Biology Lecture 16 - Trimeric G-protein coupled receptors ? 2011 Grant MacGregor & Christine S ü tterlin All rights ponents and events of a generic monomeric GTPase cycle - how do they work ? ? GAP - G TPase a ctivating p rotein (greatly increases rate at which GTPase hydrolyses GTP, thus reduces time that GTPase is on ). ? GEF - g uanine nucleotide e xchange f actor (stimulates exchange of GDP for GTP, helps turn GTPase on ) ? GDI - g uanine nucleotide d issociation i nhibitor ( prevents loss of GDP from GTPase, helps keep GTPase off ) Inactive Active Note - GDP-bound GTPases do not bind to, or activate effectors without first