CHANGES IN THE EXPRESSION OF GUANINE-NUCLEOTIDE-BINDING PROTEINS DURING DIFFERENTIATION OF 3T3-F442A CELLS IN A HORMONALLY DEFINED MEDIUM

Using specific antisera, the expression of the G protein alpha subunit s, G8, G(i1), G(i2), G(i3) and G0, were determined in 3T3-F442A cells during their differentiation to adipocytes in a hormonally defined med ium. Differentiation caused distinct increases in the expression of tw o G(s) isoforms and decreases in the expression of both G(i2) and G(i3 ). Differentiation also resulted in a 2- to 4-fold increase in forskol in-stimulated adenylyl cyclase activity and a 15-fold increase in the response of cells to a beta-adrenergic agonist. The increase in G, exp ression was also observed, to a lesser degree, in cells maintained at confluence under conditions where morphological conversion was negligi ble and the decreased expression of G(i2) and G(i3) and the increased beta-adrenergic responsiveness did not occur.