Phospholipase D (PLD) is distributed widely in nature, being present in various isoforms in
bacteria, protozoa, fungi, plants, and animals. It catalyzes the hydrolysis of phospholipids,
primarily phosphatidylcholine (PC), into phosphatidic acid (PA) and the head group, choline.
It also catalyzes a transphosphatidylation reaction in which water is replaced by a primary
alcohol to yield a phosphatidyl alcohol. This reaction is exclusive to PLD and is employed as
a specific assay for the enzyme in in vivo systems. When the purified enzyme is assayed in …