Opiate-dependent modulation of adenylate cyclase.

Publisher Website
Google Scholar
Abstract
Reactions mediated by opiate receptors that inhibit adenylate cyclase (EC 4.6.1.1) are closely coupled to subsequent reactions that gradually increase adenylate cyclase activity of [mouse] neuroblastoma .times. glioma NG108-15 hybrid cells. Opiate-treated cells have higher basal-, prostaglandin E1- and 2-chloroadenosine-stimulated activities than do control cells. NaF or guanosine 5''-(.beta.,.gamma.-imido)triphosphate abolishes most of the difference in adenylate cyclase activity observed with homogenates from control and opiate-treated cells. Cycloheximide blocked some, but not all, of the opiate-dependent increase in adenylate cyclase activity. The opiate-dependent increase in adenylate cyclase may be due to conversion of adenylate cyclase to a form with altered activity. Protein synthesis is required for part of the opiate effect. Adenylate cyclase activity probably determines the rate of enzyme conversion from 1 form to other other, and opiates, by inhibiting adenylate cyclase, alter the relative abundance of low- and high-activity forms of the enzyme.