Biosynthesis of phosphatidylcholine in the fat body of Phormia regina larvae

Abstract

The biosynthesis of phosphatidylcholine from choline by the intact fat body of larval Phormia regina as well as by cell-free preparations from the fat body has been demonstrated. ATP and CTP stimulate this synthesis. O-phosphorylcholine and cytidine diphosphate choline are intermediates and time course studies indicate that the pathway proceeds in the following sequence: choline→O-phosphorylcholine→cytidine diphosphate choline→phosphatidycholine, as has been demonstrated in other animals. Studies with subcellular fractions indicate that choline kinase (ATP: choline phosphotransferase, E.C. 2.7.1.32) and phosphorylcholine cytidyltransferase (CTP: choline phosphate cytidyltransferase, E.C. 2.7.7.14) are located in the 100,000 g supernatant whereas phosphorylcholine glyceride transferase (cytidine diphosphate choline: 1,2: diglyceride cholinephosphotransferase, E.C. 2.7.8.2) appears in the particulate fraction.