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Ca 2+ and Phospholipid‐Dependent Protein Kinase Activity and Phosphorylation of Endogenous Proteins in Bovine Adrenal Medulla
Author(s) -
Wise Bradley C.,
Costa Erminio
Publication year - 1985
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1985.tb05497.x
Subject(s) - adrenal medulla , endogeny , phospholipid , phosphorylation , medulla , biochemistry , chemistry , protein kinase a , microbiology and biotechnology , biology , endocrinology , catecholamine , membrane
Soluble and membrane fractions of bovine adrenal medulla contain several substrates for the Ca 2+ / phospholipid‐dependent and cyclic AMP‐dependent protein kinases. The phosphorylation of soluble proteins (36 and 17.7 kilodaltons) and a membrane protein (22.5 kilo‐daltons) showed an absolute requirement for the presence of both Ca 2+ and phosphatidylserine; other substrates showed less stringent phosphorylation requirements and many of these proteins were specific for each of the protein kinases. The Ca 2+ /phospholipid‐dependent phosphorylation was rapid, with effects seen as early as at 30 s of incubation. Measurement of enzyme activities with histone HI as an exogenous substrate demonstrated that the Ca 2+ /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 Ca 2+ /phos‐pholipid‐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 Ca 2+ /phospholipid‐dependent protein kinase in chromaffin cell function.