Physical dissociation of G protein heterotrimers in living cells

Abstract

In addition to providing a clear demonstration of G protein dissociation, we also propose a more complete model of the G protein cycle where active G proteins are in continuous association-dissociation equilibrium. Accordingly, at any given time during activation, G protein heterotrimers can cycle through several dissociation-association events until GTP ·is hydrolyzed. A model of the ·G protein cycle where GaGrP + Gl3y and GaGrPGI3y are both present during activation is included.