PHOSPHATIDYLSERINE SYNTHASE-I AND SYNTHASE-II OF MAMMALIAN-CELLS

Phosphatidylserine (PtdSer) in mammalian cells is synthesized through an exchange of free L-serine for the base moiety of pre-existing phosp holipids. Studies on PtdSer biosynthesis in Chinese hamster ovary (CHO ) cells have suggested that the serine base-exchange is catalyzed by a t least two different enzymes; one, named PtdSer synthase I (PSS I), u ses phosphatidylcholine (PtdCho) and possibly phosphatidylethanolamine (PtdEtn) as phosphatidyl donors for the serine base-exchange, and the other, named PtdSer synthase II (PSS II), uses PtdEtn but not PtdCho as a phosphatidyl donor. Recently, cDNAs of the PSS I and II have been isolated from CHO-K1 cells. This review will briefly describe the cur rent understanding of PtdSer synthases of mammalian cells, mainly CHO cells. (C) 1997 Elsevier Science B.V.