JUVENILE-HORMONE DEPENDENT PHOSPHORYLATION OF A 100 KDA POLYPEPTIDE IS MEDIATED BY PROTEIN-KINASE-C IN THE FOLLICLE CELLS OF RHODNIUS-PROLIXUS

The addition of juvenile hormone I (JH I) to membrane preparations of the follicle cells from vitellogenic follicles of the insect Rhodnius prolixus causes a significant increase in the phosphorylation of a 100 kDa polypeptide; and ouabain, a specific inhibitor of Na+K+-ATPase, e liminates this effect. H-7 (1-(5-isoquinolinesulfonyl)-2-methylpiperaz ine), an inhibitor of protein kinase C (PKC), also eliminates the JH-d ependent phosphorylation of this polypeptide. PDBU (phorbol-12,13-dibu tyrate), an activator of PKC, mimics the action of JH in increasing th e phosphorylation of the 100 kDa polypeptide. Because these findings p arallel the action of JH in causing the patency, the appearance of lar ge spaces between the follicle cells through which vitellogenin gains access to the oocyte surface, they suggest that phosphorylation of one or more membrane proteins is a key event in the development of patenc y in response to JH. The 100 kDa polypeptide may represent the alpha-s ubunit of Na+K+-ATPase.