Characterization of phosphatidylthreonine in polyoma virus transformed fibroblasts.

A threonine phospholipid in polyoma virus-transformed hamster embryo fibroblasts has been characterized as phosphatidylthreonine. The identification has been made by chemical and enzymatic hydrolysis. Acid hydrolysis of the phospholipid produces free threonine. Mild alcoholysis produces a water-soluble derivative having the properties of glycerophosphorylthreonine. Hydrolysis with phospholipase C produces phosphorylthreonine which on prolonged acid hydrolysis yields threonine. Phosphatidylthreonine in the cell is more accessible to reaction with fluorodinitrobenzene than is phosphatidylserine. Phosphatidylthreonine also has been found as a major aminophospholipid in two other polyoma-transformed hamster cell lines and in the BHK-21/C13 line including the PVT-3 and TS-3 lines. the latter derived from BHK cells. Only a trace amount of phosphatidylthreonine occurs in normal liver, kidney and spleen of the adult mouse, in normal liver and kidney of the adult hamster, in whole mouse and hamster embryos, and in mouse 3T3 cells and SV40-transformed 3T3 cells.