STEPWISE ACCELERATION OF PHOSPHATIDYL CHOLINE SYNTHESIS IN PHYTOHEMAGGLUTININ-TREATED LYMPHOCYTES

Phytohemagglutinin accelerates the incorporation of labeled choline into total lymphocyte lipid(> 95% in phosphatidyl choline) in a stepwise manner. The early acceleration of choline incorporation (0-2 h) is independent of protein synthesis while the late acceleration (24-48 h) is dependent upon protein synthesis. The labeling of phosphatidyl choline by [Me-14C]methionine is also accelerated by phytohemagglutinin. Phytohemagglutinin stimulates the accumulation first of phosphatidyl ethanolamine and phosphatidyl serine (0-24 h), then of phosphatidyl choline and phosphatidyl inositol (24-48 h). A model is presented for the roles that these stepwise alterations in phospholipid metabolism play in growth induction by phytohemagglutinin. © 1969.