cAMP inhibits translation by inducing Ca2+/calmodulin-independent elongation factor 2 kinase activity in IPC-81 cells

Treatment of IPC-81 cells led to inhibition of protein synthesis, which was accompanied by an increase in the average size of polysomes and a decrease d rate of elongation, indicating that it involved inhibition of peptide cha in elongation. This inhibition was also associated with increased phosphory lation of elongation factor eEF2 (which inhibits its activity) and enhanced Ca2+/calmodulin-independent activity of eEF2 kinase, Previous work has sho wn that phosphorylation of eEF2 kinase by cAMP-dependent protein kinase (cA PK) in vitro induces such activator-independent activity, and the present d ata show that such a mechanism can occur in intact cells to link physiologi cal levels of cAPK activation with inhibition of protein synthesis. (C) 199 9 Federation of European Biochemical Societies.