信號分子與信號轉(zhuǎn)導signalingtransdu-免費閱讀
【正文】 ? 細胞內(nèi)的信號轉(zhuǎn)導系統(tǒng)具有通用性；細胞內(nèi)一些信號轉(zhuǎn)導分子和信號轉(zhuǎn)導通路需要為不同的受體所共用，但是各種細胞又有其特殊的方式嚴格控制信號轉(zhuǎn)導的特異性流向。 ? 下游分子包括 PLCγ、 MAPK家族的活化，并有多種銜接蛋白參與。 ? 酶偶聯(lián)受體種類繁多，但是以具有 PTK活性和與 PTK偶聯(lián)的受體居多。? Classification of phosphatase according to the Amino acid sequence in active center ?Ser/Thr phosphatase ?Tyr phosphatase ?Dual specificity Ⅱ . G protein/small G protein ? guanine nucleotide binding protein， G protein（鳥苷酸結(jié)合蛋白）亦稱 GTP結(jié)合蛋白 a signal molecule in various pathways, functioning differently in different cells ? Two forms of G protein G protein binding with GTP: its active form GTP hydrolysed to GDP: inactive form ? 2 types of G protein ： ? Heterotrimer G protein:（ Gα） ,β,γ(Gβγ) binding with receptor with 7 transmembrane dormains， ? Small G protein (21kD） 1. Heterotrimer G protein mediated receptor signal directly Gα Gβγ Multiple Sites αsubunit with GTPase act. Binding site with receptor Bingding site withβγsubunits GDP/GTP binding site Binding with dwonstream molecules formed a plex with Gα,localized in Βγregulate targeted protein directlyin mammalian The activation/deactivation cycle for hormonally stimulated adenylate cyclase ? G proteincoupled receptors， GPCRs Ligand GPCRs –G protein（ AC,PLC… )cell function The role of PIP2 in intracellular signaling 2. Ras surperfamily: important signal molecules ? Small G protein （ 21kD）， functioning as switch ? Ras is a first discoved G protein Ras family: each contains a GTPase domain ? Factors control small G protein act. ?Factor increasing act. ： ? guanine nucleotide exchange factor (GEF) ? guanine nucleotide release protein (GNRP) ?Factor decreasing act.： ? guanine nucleotide dissociation inhibitor (GDI) ? GTPase activation protein (GAP) Ras activation and its regulators GTP GDP Ras Ras SOS GAP on off Summary of Section 3 1. Proteins are the main ponents of signaling pathways 2. Proetin kinases and phosphotases are
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