Cholera toxin treatment produces down-regulation of the α-subunit of the stimulatory guanine-nucleotide-binding protein (Gs)

摘要: The effect of activation the alpha-subunit(s) stimulatory guanine-nucleotide-binding protein, Gs, on levels this polypeptide(s) associated with plasma membrane L6 skeletal myoblasts was ascertained. Incubation these cells cholera toxin led to a time- and concentration-dependent 'down-regulation' both 44 42 kDa forms Gs alpha as assessed by immunoblotting an anti-peptide antiserum (CS1) able identify extreme C-terminus Gs. specific for Gs; Gi in membranes toxin-treated were not different from untreated cells. Down-regulation absolutely dependent upon prior ADP-ribosylation, hence mimicked other agents which elevate intracellular cyclic AMP. Pretreatment pertussis toxin, catalyses ADP-ribosylation but did down-regulate either or demonstrating that covalent modification is alone signal removal G-proteins membrane.