Possible phospholipid precursor for phosphatidylserine in rat heart.

The incorporation of 32-P-labelled inorganic phosphate into phospholipids of rat heart slices was investigated in pulse-chase experiments. The comparison of the specific activities of individual phospholipids suggested that phosphatidic acid can be 32P precursor for phosphatidylserine. Studies with L-serine revealed the full calcium dependence of phosphatidyslserine formation in heart homogenates. Chasing experiments with [1,2-14C]ethanolamine and [methyl-14C]choline proved the precursor role of phospholipids phosphatidic acid was the most potent in stimulating phosphatidylserine formation in homogenates. The conclusion was reached that phosphatidic acid can also be regarded as precursor for phosphatidylserine.