Enables glycerol-3-phosphate O-acyltransferase activity. Involved in glycerol-3-phosphate metabolic process; phospholipid biosynthetic process; and triglyceride biosynthetic process. Located in endoplasmic reticulum. Orthologous to human GPAT3 (glycerol-3-phosphate acyltransferase 3). [provided by Alliance of Genome Resources, Apr 2022]