Esterifies acyl-group from acyl-ACP to the sn-1 position of glycerol-3-phosphate, an essential step in glycerolipid biosynthesis. Involved in pollen development, by being required for tapetum differentiation and male fertility. In addition to the sporophytic effect, it also exerts a gametophytic effect on pollen performance. an acyl-CoA + sn-glycerol 3-phosphate = a 1-acyl-sn-glycero-3-phosphate + CoA Phospholipid metabolism; CDP-diacylglycerol biosynthesis; CDP-diacylglycerol from sn-glycerol 3-phosphate: step 1/3. According to PubMed:12897259 it is mitochondrial. However, no clear transit peptide is predicted by sequence analysis tools. Highly expressed in developing siliques and flower buds. Weakly or not expressed in roots, seedlings and leaves. The HXXXXD motif is essential for acyltransferase activity and may constitute the binding site for the phosphate moiety of the glycerol-3-phosphate. Plants display a massive pollen development arrest due to a perturbed degeneration of the tapetum, which is associated with altered endoplasmic reticulum profiles and reduced secretion. Defects correlate with several fatty acid composition changes in flower tissues and seeds. However, no significant change in seed oil content is observed. Belongs to the GPAT/DAPAT family.