title: Ca2+ and phospholipid-dependent protein kinase activity and phosphorylation of endogenous proteins in bovine adrenal medulla.
abstract: Soluble and membrane fractions of bovine adrenal medulla contain several substrates for the Ca2+/phospholipid-dependent and cyclic AMP-dependent protein kinases. The phosphorylation of soluble proteins (36 and 17.7 kilodaltons) and a membrane protein (22.5 kilodaltons) showed an absolute requirement for the presence of both Ca2+ and phosphatidylserine; other substrates showed less stringent phosphorylation requirements and many of these proteins were specific for each of the protein kinases. The Ca2+/phospholipid-dependent phosphorylation was rapid, with effects seen as early as at 30 s of incubation. Measurement of enzyme activities with histone H1 as an exogenous substrate demonstrated that the Ca2+/phospholipid-dependent protein kinase was equally distributed between the soluble and membrane fractions whereas the cyclic AMP-dependent enzyme was predominantly membrane-bound in adrenal medulla and chromaffin cells. The activity of the soluble Ca2+/phospholipid-dependent protein kinase of adrenal medulla was found to be about 50% of the enzyme level present in rat brain, a tissue previously shown to contain a very high enzyme activity. These results suggest a prominent role for the Ca2+/phospholipid-dependent protein kinase in chromaffin cell function.
authors.forename: B C
authors.initials: BC
authors.lastname: Wise
authors.forename: E
authors.initials: E
authors.lastname: Costa
mesh_terms: D000313:Adrenal Medulla / Q000201:enzymology*; D000818:Animals; D002118:Calcium / Q000494:pharmacology*; D002417:Cattle; D002462:Cell Membrane / Q000378:metabolism; D002838:Chromaffin System / Q000201:enzymology; D000242:Cyclic AMP / Q000494:pharmacology; D006152:Cyclic GMP / Q000494:pharmacology; D003600:Cytosol / Q000378:metabolism; D007700:Kinetics; D008970:Molecular Weight; D010718:Phosphatidylserines / Q000494:pharmacology; D010743:Phospholipids / Q000494:pharmacology*; D010750:Phosphoproteins / Q000378:metabolism*; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism*
chemical_list: D010718:Phosphatidylserines; D010743:Phospholipids; D010750:Phosphoproteins; D000242:Cyclic AMP; D011494:Protein Kinases; D006152:Cyclic GMP; D002118:Calcium