The intracellular phospholipase A1 protein family

Phospholipase A1 is an enzyme that hydrolyzes phospholipids, producing 2-acyl-lysophospholipids and fatty acids. The intracellular phospholipase A1 (iPLA1) protein family is a relatively recently discovered lipid-metabolizing enzyme family. Lower eukaryotes, such as yeasts and nematodes, and plants have only one iPLA1 protein, whereas mammals have three iPLA1 family proteins (PA-PLA1/DDHD1/iPLA1α, p125/Sec23IP/iPLA1β and KIAA0725p/DDHD2/iPLA1γ). Mammalian iPLA1 proteins are localized in different cellular compartments, and two of them, p125 and KIAA0725p, have been implicated in membrane trafficking events. Recent gene targeting studies on several organisms showed that iPLA1 family proteins are involved in various physiological functions, including plant shoot gravitropism, epithelial stem cell differentiation and spermiogenesis. In this review, we describe the features of iPLA1 family proteins and recent progress regarding our understanding of their physiological functions.