Catalyzes the terminal and only committed step in triacylglycerol synthesis by using diacylglycerol and fatty acyl CoA as substrates. Required for storage lipid synthesis (By similarity). a 1,2-diacyl-sn-glycerol + an acyl-CoA = a triacyl-sn-glycerol + CoA all-trans-retinol + an acyl-CoA = an all-trans-retinyl ester + CoA (9Z)-octadecenoyl-CoA + 2-(9Z-octadecenoyl)-glycerol = 1,2-di-(9Z-octadecenoyl)-sn-glycerol + CoA (9Z)-octadecenoyl-CoA + 1,2-di-(9Z-octadecenoyl)-sn-glycerol = 1,2,3-tri-(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-(9Z-octadecenoyl)-glycerol = 1,2-di-(9Z-octadecenoyl)-glycerol + CoA 1,2-di-(9Z-octadecenoyl)-sn-glycerol + hexadecanoyl-CoA = 1,2-di-(9Z)-octadecenoyl-3-hexadecanoyl-sn-glycerol + CoA (9Z)-octadecenoyl-CoA + 1,3-di-(9Z-octadecenoyl)-glycerol = 1,2,3-tri-(9Z-octadecenoyl)-glycerol + CoA (9Z)-octadecenoyl-CoA + 2,3-di-(9Z)-octadecenoyl-sn-glycerol = 1,2,3-tri-(9Z-octadecenoyl)-glycerol + CoA 2-(9Z-octadecenoyl)-glycerol + hexadecanoyl-CoA = 1-hexadecanoyl-2-(9Z-octadecenoyl)-sn-glycerol + CoA Glycerolipid metabolism; triacylglycerol biosynthesis. Belongs to the diacylglycerol acyltransferase family.