Biochemical and Biophysical Research Communications, Vol.421, No.3, 605-611, 2012
All G protein beta gamma complexes are capable of translocation on receptor activation
Heterotrimeric G proteins transduce signals sensed by transmembrane G protein coupled receptors (GPCRs). A subfamily of G protein beta gamma subunit types has been shown to selectively translocate from the plasma membrane to internal membranes on receptor activation. Using 4D imaging we show here that G beta gamma translocation is not restricted to some subunit types but rather all 12 members of the family of mammalian gamma subunits are capable of supporting beta gamma translocation. Translocation kinetics varies widely depending on the specific gamma subunit type, with t(1/2) ranging from 10 s to many minutes. Using fluorescence complementation, we show that the beta and gamma subunits translocate as beta gamma dimers with kinetics determined by the gamma subunit type. The expression patterns of endogenous gamma subunit types in HeLa cells, hippocampal neurons and cardiomyocytes are distinctly different. Consistent with these differences, the beta gamma translocation rates vary widely. beta gamma translocation rates exhibit the same gamma subunit dependent trends regardless of the specific receptor type or cell type showing that the translocation rates are intrinsic to the gamma subunit types. beta gamma complexes with widely different rates of translocation had differential effects on muscarinic stimulation of GIRK channel activity. These results show that G protein beta gamma translocation is a general response to activation of GPCRs and may play a role in regulating signaling activity. (C) 2012 Elsevier Inc. All rights reserved.