Phosphatidylethanolamine derived from phosphatidylserine is deacylated and reacylated in rat hepatocytes

The metabolism of phosphatidylserine (PS), phosphatidylethanolamine (PE) and phosphatidylcholine (PC), derived from [3H]serine, has been studied in rat hepatocytes. After an initial pulse with radioactivity for 10 min and a chase for up to 240 min, cells were harvested and PS, PE and PC isolated. At the end of the pulse, greater than 90% of [3H]serine derived phospholipid radioactivity was associated with PS. In the subsequent chase, newly-made PS was degraded rapidly with less than 25% of the label lost from PS appearing in the PE and PC pools. In contrast, [3H]serine-labeled PE turnover was not detectable. Very little newly-made PS was converted to PC. PE and PC were further fractionated into molecular species by high-performance liquid chromatography. We report that [3H]serine-labeled PE is deacylated/reacylated with the major product of remodeling being 18:0-20:4 PE. In contrast, [3H]serine-labeled PC is not significantly remodeled.