Continuous growth and phosphatidylcholine synthesis of rat hepatoma cells in choline-deprived chemically defined medium

A choline non-required cell line was established from a rat hepatoma cell line. The line designated R-Y121B·cho was able to grow in choline-deprived medium without serum and lipid. Choline is necessary for the biosynthesis of phosphatidylcholine, which is a main component of cell membranes. Phosphatidylcholine can be synthesized by the methylation of phosphatidyletha-nolamine in liver cells. Phospholipid composition and incorporation of radiolabeled serine into phosphatidylserine or phosphatidylethanolamine were quite similar in R-Y121B cho and its parental cells. However R-Y121B cho cells had higher phosphatidylcholine synthesis activity from radiolabeled methionine than parental cells. These results indicate that choline requirement of mammalian cells depends on the activity of phosphatidylethanolamine methyltransferase.