Enzymes of phospholipid synthesis in Bacillus Calmette-Guerin induced rabbit alveolar macrophage. Characterization and localization of cytidine diphosphocholine phosphotransferase and monoacylphospholipid acyltransferase.
The rabbit alveolar macrophage is capable of renewing its plasma membrane by at least two metabolic pathways. It contains (1) a monoacylphospholipid acyltransferase, which catalyzes the synthesis of diacylphospholipids by recycling monoacylphospholipids produced by the action of phospholipases and (2) a cytidine diphosphocholine phosphotransferase (CDPcholine phosphotransferase), which catalyzes the last step in the synthesis de novo of diacylglycerophosphocholine. These activities have been characterized in the cell homogenate with respect to time, protein, pH optimum (for CDPcholine phosphotransferase), substrate specificity (for monoacylphospholipid acyltransferase) and cation requirement ( for CDPcholine phosphotransferase). Monoacylphospholipid acyltransferase activity is localized solely in the endoplasmic reticulum. On the other hand, the CDPcholine phosphotransferase activity can be measured in the endoplasmic reticulum and in the plasma membrane, characterized by both differential and gradient sedimentation techniques. In addition to the normal route of phospholipid synthesis in the endoplasmic reticulum, the rabbit alveolar macrophage may thus possess the capacity for in situ synthesis of phospholipids of plasma membrane as a mechanism for membrane renewal following phagocytosis.
D000217:Acyltransferases / Q000378:metabolism*; D000818:Animals; D001500:BCG Vaccine; D006801:Humans; D007700:Kinetics; D008264:Macrophages / Q000201:enzymology*; D009504:Neutrophils / Q000201:enzymology; D010743:Phospholipids / Q000378:metabolism*; D010770:Phosphotransferases / Q000378:metabolism*; D011650:Pulmonary Alveoli / Q000201:enzymology*; D011817:Rabbits
D001500:BCG Vaccine; D010743:Phospholipids; D000217:Acyltransferases; D010770:Phosphotransferases