THE BETA-GAMMA-SUBUNITS OF HETEROTRIMERIC G-PROTEINS ACQUIRE DETERGENT INSOLUBILITY DIRECTLY AT THE PLASMA-MEMBRANE

The subunits of heterotrimeric G proteins, G alpha and G beta gamma, a re found in association with detergent-resistant domains in most mamma lian cell types, implicating such domains in G protein-coupled signali ng. The pathway by which the beta gamma complexes are targeted to thes e detergent-resistant domains was unaffected by the brefeldin A-impose d block on endoplasmic reticulum-to-Golgi transport. We have used subc ellular fractionation and beta subunit-specific immunoprecipitation to localize the acquisition of detergent insolubility of newly synthesiz ed beta gamma complexes. The beta subunits cofractionate with plasma m embranes, and acquire detergent insolubility coincident with arrival i n the plasma membrane fractions. This association was not affected by phorbol 12-myristate 13-acetate-induced activation of Protein kinase C . (C) 1997 Federation of European Biochemical Societies.