Phospholipase C activity in plasma membranes isolated from lapine synovial cells in monolayer culture

Plasma membranes were isolated from lapine synovial cells grown in monolayer culture using discontinuous sucrose gradient centrifugation techniques. 5′nucleotidase was detected in great abundance while glucose-6 phosphate dehydrogenase and cytochrome oxidase were present at low to undetectable levels. Plasma membranes incubated at 37°C for 60 min with [3H]-arachidonyl-phosphatidylinositol/phosphatidylserine synthesized [3H]-diacylglycerides. Little if any [3H]-diacylglyceride synthesis was measured when [3H]-arachidonyl-phosphatidylcholine or [3H]-arachidonyl-phosphatidylethanolamine were used as substrates. These results are consistent with a plasma membrane-associated phosphatidylinositol-specific phospholipase C from lapine synovial cells in culture.