[Studies of phosphorylation in rat mast cells (third report)--isolation of calcium-activated, phospholipid, diacylglycerol-dependent protein kinase from rat basophilic leukemia cells (RBL-1 cells)].

Evidence is presented that RBL-1 cells, which are similar to normal rat mast cells in morphology and contain IgE receptors and histamine, contain a calcium-activated, phospholipid, diacylglycerol-dependent protein kinase. This enzyme is very similar in its activation requirements to the calcium-dependent enzyme termed protein kinase C in other tissues. The enzyme is activated by Ca2+. Diolein, but not other di, mono or triglycerides, substantially increases the enzyme activity. Among various phospholipids, phosphatidylserine is the most reactive activator; phosphatidylinositol, phosphatidic acid and phosphatidylethanolamine are less effective; and phosphatidylcholine is practically inactive. The enzyme is inhibited by chlorpromazine and local anesthetics such as dibucaine, tetracaine and procaine.