Modulation of guanine triphosphate nucleotide binding to p21ras immunoprecipitates of rat liver plasma membranes by agents affecting redox state.

GTP-gamma-[35S] and GTP-gamma-[32P] or GTP-alpha-[32P] bound to plasma membranes of rat liver was immunoprecipitated using anti p21V-H-ras. Binding was enhanced approximately 2-fold by incubation with an exogenous electron acceptor, potassium ferricyanide (but not with potassium ferrocyanide), or oxidized ubiquinone10 and was inhibited or unaffected by incubation with reduced pyridine nucleotides (NADH or NADPH) or reduced ubiquinone10. The results suggest a mechanism of guanine nucleotide exchange that is responsive to oxidation-reduction.