Calcium- and lipid-dependent protein phosphorylation in the human ovary

The cytosol of human ovarian tissues was observed to promote protein phosphorylation in the combined presence of Ca2+, 1,2-diolein, and phosphatidylserine. Ca2+ alone or lipid alone did not produce full activation of this protein kinase(s). The addition of human erythrocyte calmodulin to the assay mixture, in the presence or absence of Ca2+, had no effect on protein kinase activity. Phosphorylation of cytosol proteins ranging in mol wt from 10,000 to 200,000 was selectively increased by Ca2+ plus lipid. This protein kinase activity may play a crucial role in the intracellular transmission of the action of hormones affecting cellular Ca2+ flux and/or phospholipid metabolism.