These compositions are mediated by interactions between phenotypic expression and cellular nutrition, which determine the specificities of the enzymes of phospholipid synthesis and hydrolysis and of the transfer proteins that exchange phospholipid species between different membranes. Regulation of synthesis is best characterized for the formation of PC in rat hepatocytes, where PC synthesis is essential for assembly and secretion of very low-density lipoprotein particles, and in the lung epithelial cells responsible for synthesis of pulmonary surfactant phospholipid. Phos-phatidylcholine species synthesized de novo from dia-cylglycerol by the enzyme cholinephosphotransferase are subsequently modified by acyl remodeling mechanisms involving sequential actions of phospho-lipase and acyltransferase activities. The rate of PC synthesis is thought to be dependent on the activity of CTP:choline phosphate cytidylyltransferase (CCT), which is subject to complex regulatory mechanisms involving phosphorylation and reversible enzyme
Was this article helpful?