Translocation of G-protein beta 3 subunit from the cytosol pool to the membrane pool by beta 1-adrenergic receptor stimulation in perfused rat hearts

To elucidate the intracellular function and localization of the heterotrime ric G-protein beta 3 subunit (G beta 3) in the heart, we studied the effect s of subtype-specific beta-adrenergic receptor (beta-AR) stimulation on G b eta 3 localization using isoform-specific antibodies. The amount of G beta 3 in the cytosol dramatically decreased in hearts perfused with isoproteren ol (ISO) alone or ISO with ICI 118551, a beta 2-AR antagonist. Propranolol or CGP 20712A, a beta 1-AR antagonist, blocked the ISO-induced decrease in the G beta 3 content of the cytosol. In contrast, G beta 3 content of the m embrane fraction significantly increased in hearts perfused with ISO alone or ISO with ICI 118551. We conclude that stimulation of the beta 1-AR induc es isoform-specific translocation of G beta 3 from the cytosol to the membr ane fraction in rat hearts. (C) 1999 Elsevier Science Inc.