GPAT2 is a mitochondrial outer membrane enzyme catalyzing the first rate-limiting step in glycerolipid synthesis by transferring acyl groups from acyl-CoA to glycerol-3-phosphate, producing lysophosphatidic acid and subsequently phosphatidic acid 1. The enzyme preferentially utilizes arachidonoyl-CoA as substrate and is uniquely required for piRNA biogenesis through a mechanism independent of its acyltransferase activity 2. GPAT2 expression is restricted to male germ cells and cancer cells under physiological conditions 3. In spermatogenesis, GPAT2 is essential for normal germ cell development; its absence triggers germ cell apoptosis and arrests development at the pachytene stage 3. Biallelic GPAT2 variants cause human male infertility through impaired piRNA biogenesis, leading to transposon de-repression and germ cell loss 2. In breast cancer, GPAT2 overexpression promotes tumor progression by preventing arachidonic acid-induced apoptosis and modulating membrane properties including cell roughness and permeability 45. GPAT2 may contribute to metabolic disorders including hepatic steatosis and insulin resistance 6. The protein contains two transmembrane segments with enzymatically active motifs facing the cytosol 7.