ABSTRACT
Incubation of purified rat kidney mitochondrial fraction with phospholipase- D resulted in the accumulation of phosphatidic acid in the membrane due to the degradation of membrane-bound phosphatidylcholine, -serine and -ethanolamine Simultaneously with the hydrolysis of the phospholipids, cholesterol and protein were released from the mitochondrial membrane into the medium, and binding of Ca2+ by mitochondrial membranes increased. Phospholipase Dtreated mitochondrial fraction exhibited increased swelling in vitro in the early stages of incubation (15 min) after which the mitochondria were ruptured. Membrane- bound adenosine triphosphatase was partially inactivated and the enzyme activity was not significantly restored by incubation with sonicated dispersions of phosphatidylcholine, -serine and cholesterol. These results indicate that removal of choline, serine and ethanolamine from membrane-bound phospholipids disrupt phospholipid-cholesterol and phospholipid-protein association and affect functions of the membrane.