Using specific antisera, the expression of the G protein α subunits, G8, gi1, Gi2, Gi3, and G0, were determined in 3T3-F442A cells during their differentiation to adipocytes in a hormonally defined medium. Differentiation caused distinct increases in the expression of two Gs isoforms and decreases in the expression of both Gi2 and Gi3. Differentiation also resulted in a 2- to 4-fold increase in forskolin-stimulated adenylyl cyclase activity and a 15-fold increase in the response of cells to a β-adrenergic agonist. The increase in Gs expression was also observed, to a lesser degree, in cells maintained at confluence under conditions where morphological conversion was negligible and the decreased expression of Gi2 and Gi3 and the increased β-adrenergic responsiveness did not occur.
