The epidermal growth factor receptor is coupled to a pertussis toxin-sensitive guanine nucleotide regulatory protein in rat hepatocytes.

摘要: Activation of epidermal growth factor (EGF) receptors stimulates inositol phosphate production in rat hepatocytes via a pertussis toxin-sensitive mechanism, suggesting the involvement G protein process. Since first event after receptor-G interaction is exchange GTP for GDP on protein, effect EGF was measured initial rates guanosine 5‘-O-(3-[35S]thiotriphosphate) [( 35S]GTP gamma S) association and [alpha-32P]GDP dissociation hepatocyte membranes. The rate [35S]GTP S binding stimulated by EGF, with maximal observed at 8 nM EGF. also increased dissociation. blocked boiling peptide 5 min mM dithiothreitol or incubation membranes 5‘-O-(2-thiodiphosphate) (GDP beta S). EGF-stimulated completely abolished prepared from toxin-treated rats inhibited that were treated directly resolved A-subunit toxin. amount guanine nucleotide affected occupation receptor approximately 6 pmol/mg membrane protein. Occupation angiotensin II receptors, which are known to couple proteins hepatic membranes, antagonist [Sar1,Ile8]angiotensin II, demonstrating receptor-mediated. In A431 human epidermoid carcinoma cells, lipid breakdown, but not treatment cells these had no binding. beta-adrenergic cell isoproterenol did stimulate [35S] binding, could be l-propranolol. These results support concept interact mechanism similar other hormone interactions, may activate phospholipase C different mechanisms.