Catalyzes the transfer of an acyl group from acyl-ACP to glycerol-3-phosphate (G3P) to form lysophosphatidic acid (LPA). This enzyme can also utilize acyl-CoA as fatty acyl donor, but not acyl-PO(4). an acyl-CoA + sn-glycerol 3-phosphate = a 1-acyl-sn-glycero-3-phosphate + CoA a fatty acyl-[ACP] + sn-glycerol 3-phosphate = a 1-acyl-sn-glycero-3-phosphate + holo-[ACP] Lipid metabolism; phospholipid metabolism. Probably interacts with PlsX. Belongs to the PlsY family.