Regulation and possible role of mammalian phospholipase D in cellular functions.

Phospholipase D (PLD), an enzyme widely distributed in bacteria, fungi, plants, and animals, catalyzes the hydrolysis of phosphatidylcholine (PC) and other phospholipids to generate phosphatidic acid (PA). PLD activity can lead to the generation of phosphatidylalcohol in the presence of a primary alcohol. This reaction, referred to as transphosphatidylation, is not only a hallmark of PLD activity but has also been used to block the production of PA in functional studies. PLD activity in mammalian cells is transiently increased following the occupation of many cell surface receptors, including those of the heterotrimeric G-protein and tyrosine kinase families (1-4). The generated PA and the further metabolites, 1,2diacylglycerol (DG) and lysoPA, are important biologically-active products that are able to recruit or modulate specific target proteins. This review will focus on recent developments in regulation of the mammalian PLD isozymes involved in cell stimulation and on the functional roles of PLD signaling.