Catalyzes the formation of diacylglycerol from 2-monoacylglycerol and fatty acyl-CoA. Also able to catalyze the terminal step in triacylglycerol synthesis by using diacylglycerol and fatty acyl-CoA as substrates. Has a preference toward palmitoyl-CoA and oleoyl-CoA. May be involved in absorption of dietary fat in the small intestine by catalyzing the resynthesis of triacylglycerol in enterocytes. Also able to use 1-monoalkylglycerol (1-MAkG) as an acyl acceptor for the synthesis of monoalkyl-monoacylglycerol (MAMAG) (PubMed:28420705). a 2-acylglycerol + an acyl-CoA = a 1,2-diacyl-sn-glycerol + CoA a 1,2-diacyl-sn-glycerol + an acyl-CoA = a triacyl-sn-glycerol + CoA (9Z)-octadecenoyl-CoA + 2-(9Z-octadecenoyl)-glycerol = 1,2-di-(9Z-octadecenoyl)-sn-glycerol + CoA 2-(9Z-octadecenoyl)-glycerol + hexadecanoyl-CoA = 1-hexadecanoyl-2-(9Z-octadecenoyl)-sn-glycerol + CoA (9Z)-octadecenoyl-CoA + 1,2-di-(9Z-octadecenoyl)-sn-glycerol = 1,2,3-tri-(9Z-octadecenoyl)-glycerol + CoA 1-hexadecanoyl-2-(9Z-octadecenoyl)-sn-glycerol + hexadecanoyl-CoA = 1,3-dihexadecanoyl-2-(9Z-octadecenoyl)glycerol + CoA all-trans-retinol + hexadecanoyl-CoA = all-trans-retinyl hexadecanoate + CoA (9Z)-octadecenoyl-CoA + 1-O-(9Z-octadecenyl)-glycerol = 1-O-(9Z-octadecenyl)-mono-(9Z-octadecenoyl)-glycerol + CoA (9Z)-octadecenoyl-CoA + 1-O-(9Z-octadecenyl)-mono-(9Z-octadecenoyl)-glycerol = 1-O-(9Z-octadecenyl)-2,3-di-(9Z-octadecenoyl)glycerol + CoA Glycerolipid metabolism; triacylglycerol biosynthesis. Selectively expressed in the digestive system. Highly expressed in the ileum, and at lower level in jejunum, duodenum, colon, cecum and the rectum. Not expressed in the stomach and the esophagus and trachea. Expressed at very low level in liver. Ubiquitinated. Ubiquitination leads to proteasomal degradation. Belongs to the diacylglycerol acyltransferase family.