Metabolic and molecular aspects of ethanolamine phospholipid biosynthesis: the role of CTP:phosphoethanolamine cytidylyltransferase (Pcyt2).

The CDP-ethanolamine branch of the Kennedy pathway is the major route for the formation of ethanolamine-derived phospholipids, including diacyl phosphatidylethanolamine and alkenylacyl phosphatidylethanolamine derivatives, known as plasmalogens. Ethanolamine phospholipids are essential structural components of the cell membranes and play regulatory roles in cell division, cell signaling, activation, autophagy, and phagocytosis. The physiological importance of plasmalogens has not been not fully elucidated, although they are known for their antioxidant properties and deficiencies in a number of inherited peroxisomal disorders. This review highlights important aspects of ethanolamine phospholipid metabolism and reports current molecular information on 1 of the regulatory enzymes in their synthesis, CTP:phosphoethanolamine cytidylyltransferase (Pcyt2). Pcyt2 is encoded by a single, nonredundant gene in animal species that could be alternatively spliced into 2 potential protein products. We describe properties of the mouse and human Pcyt2 genes and their regulatory promoters and provide molecular evidence for the existence of 2 distinct Pcyt2 proteins. The goal is to obtain more insight into Pcyt2 catalytic function and regulation to facilitate a better understanding of the production of ethanolamine phospholipids via the CDP-ethanolamine branch of the Kennedy pathway.