CYTOSOLIC LOCALIZATION OF BETA(3)-SUBUNIT OF HETEROTRIMERIC GTP-BINDING PROTEIN IN RAT HEARTS

The expression of three different subtypes of GTP binding protein beta -subunits (beta 1, beta 2 and beta 3) was examined in rat hearts at bo th mRNA and protein levels. Among three subtypes, beta 3 mRNA was more abundant in ventricles while beta 1 and beta 2 mRNAs were expressed u biquitously among ventricles, atria and aortas. The immunodetectable b eta 1- and beta 3-proteins were predominantly found in the cytosolic f raction of rat ventricles. In this study, we demonstrate ventricle-spe cific expression of beta 3-subunit and localization of G protein beta 3-subunit in the cytosol of rat hearts. This unusual cytosolic localiz ation of G protein beta(3)-subunit might indicate subtype-specific fun ction of G protein beta(gamma)-subunits in rat hearts. (C) 1995 Academ ic Press, Inc.