G-proteins L (Effector k3 S Iana
G L Effector G-proteins Signal
G蛋白偶联受体(400-600个氨基酸残基组成的多肽) G-protein-coupled receptors 与配体结合 Extracellular e2 e3 e1 -S-S TMT TM2 TM3 TM4 TM5 TM6 TMZ Q 333 12 i1 Cytoplasmic G蛋白作用部位 COOH-
Extracellular Cytoplasmic COOH- -NH2 i1 i2 i3 e1 e2 e3 TM1 TM2 TM3 TM4 TM5 TM6 TM7 D R Y G 蛋白偶联受体（400-600个氨基酸残基组成的多肽） G-protein-coupled receptors -S-S- 与配体结合 G蛋白作用部位
G蛋白亚单位( G-protein subunits) · Three subunits 4 subtypes binds gtP v activation of 2nd mess √ less variability v also activates 2nd mess V Regulation subunits
✓ 4 subtypes ✓ binds GTP ✓ activation of 2nd mess. ✓ less variability ✓ also activates 2nd mess. G蛋白亚单位（G-protein subunits） • Three subunits √ Regulation subunits
G-protein subtypes Go G G Ga12 v inhibitioncrtase& hadst er egtapRiaaAli rg between GPCR " activation of GIBKntiategnfaactienreledeseinie-stigation
Gi/o Gs Gq G12/13 ✓ inhibition of cAMP production ✓ inhibition of Ca2+ channels ✓activation of GIRK K+ channels G-protein subtypes ✓ increased synthesis of cAMP ✓activation of Ca2+ and K+ channels ✓activation of PLC leading to ✓activation of PKC (DAG) ✓intracellular Ca2+ release (IP3 ) ✓ mediates signalling between GPCRs and RhoA (GTPase) ✓ function under investigation
GPCR signalling FIrst messenger Off a G protein Receptor GDP Effector GTP GTP GDP On GDP←GTP GTP
GPCR signalling