| Abstract: | Phorbol ester treatment enhanced the catalytic activity of type II adenylyl cyclase overexpressed in insect cells. In cells coexpressing type II adenylyl cyclase and protein kinase C-α, type II adenylyl cyclase catalytic activity was higher even in the absence of phorbol ester treatment; phorbol ester treatment further and markedly enhanced type II adenylyl cyclase catalytic activity. However, this enhancement, either by phorbol ester treatment or by coexpression of protein kinase C-α, was lost following membrane solubilization with detergents. This attenuation was unaffected by phosphatase inhibitor or salts. In contrast, membrane solubilization did not affect forskolin-stimulated type II adenylyl cyclase catalytic activity. Purified type II adenylyl cyclase was stimulated by forskolin and Gsα, but not by protein kinase C-α. Therefore, a specific mammalian protein kinase C isoenzyme can activate type II adenylyl cyclase, but the mechanism clearly differs from that underlying either Gsα- or forskolin-mediated stimulation. J. Cell. Biochem. 64:492–498. © 1997 Wiley-Liss, Inc. |
