Catalyzes the formation of diacylglycerol from 2-monoacylglycerol and fatty acyl-CoA. Has a preference toward monoacylglycerols containing unsaturated fatty acids in an order of C18:3 > C18:2 > C18:1 > C18:0. Plays a central role in absorption of dietary fat in the small intestine by catalyzing the resynthesis of triacylglycerol in enterocytes. May play a role in diet-induced obesity. Also able to use 1-monoalkylglycerol (1-MAkG) as an acyl acceptor for the synthesis of monoalkyl-monoacylglycerol (MAMAG) (By similarity). a 2-acylglycerol + an acyl-CoA = a 1,2-diacyl-sn-glycerol + CoA (9Z)-octadecenoyl-CoA + 2-(9Z-octadecenoyl)-glycerol = 1,2-di-(9Z-octadecenoyl)-sn-glycerol + CoA (9Z)-octadecenoyl-CoA + 1-(9Z-octadecenoyl)-glycerol = 1,2-di-(9Z-octadecenoyl)-glycerol + CoA 2-(9Z-octadecenoyl)-glycerol + butanoyl-CoA = 1-butyryl-2-(9Z)-octadecenoyl-sn-glycerol + CoA 2-(9Z-octadecenoyl)-glycerol + octanoyl-CoA = 1-octanoyl-2-(9Z)-octadecenoyl-sn-glycerol + CoA 2-(9Z-octadecenoyl)-glycerol + dodecanoyl-CoA = 1-dodecanoyl-2-(9Z)-octadecenoyl-sn-glycerol + CoA 2-(9Z-octadecenoyl)-glycerol + tetradecanoyl-CoA = 1-tetradecanoyl-2-(9Z)-octadecenoyl-sn-glycerol + CoA 2-(9Z-octadecenoyl)-glycerol + hexadecanoyl-CoA = 1-hexadecanoyl-2-(9Z-octadecenoyl)-sn-glycerol + CoA 2-(9Z-octadecenoyl)-glycerol + octadecanoyl-CoA = 1-octadecanoyl-2-(9Z-octadecenoyl)-sn-glycerol + CoA 2-(9Z-octadecenoyl)-glycerol + eicosanoyl-CoA = 1-eicosanoyl-2-(9Z)-octadecenoyl-sn-glycerol + CoA (9Z,12Z)-octadecadienoyl-CoA + 2-(9Z-octadecenoyl)-glycerol = 1-(9Z,12Z)-octadecadienoyl-2-(9Z)-octadecenoyl-sn-glycerol + CoA (5Z,8Z,11Z,14Z)-eicosatetraenoyl-CoA + 2-(9Z-octadecenoyl)-glycerol = 1-(5Z,8Z,11Z,14Z)-eicosatetraenoyl-2-(9Z)-octadecenoyl-sn-glycerol + CoA (9Z)-octadecenoyl-CoA + 1-dodecanoylglycerol = 1-dodecanoyl-2-(9Z-octadecenoyl)-glycerol + CoA (9Z)-octadecenoyl-CoA + 1-tetradecanoylglycerol = 1-tetradecanoyl-2-(9Z-octadecenoyl)-glycerol + CoA (9Z)-octadecenoyl-CoA + 1-hexadecanoylglycerol = 1-hexadecanoyl-2-(9Z-octadecenoyl)glycerol + CoA (9Z)-octadecenoyl-CoA + 1-octadecanoylglycerol = 1-octadecanoyl-2-(9Z)-octadecenoylglycerol + CoA (9Z)-octadecenoyl-CoA + 1-(9Z,12Z-octadecadienoyl)-glycerol = 1-(9Z,12Z-octadecadienoyl)-2-(9Z-octadecenoyl)-glycerol + CoA (9Z)-octadecenoyl-CoA + 1-(9Z,12Z,15Z-octadecatrienoyl)-glycerol = 1-(9Z,12Z,15Z-octadecatrienoyl)-2-(9Z-octadecenoyl)-glycerol + CoA (9Z)-octadecenoyl-CoA + 1-(5Z,8Z,11Z,14Z-eicosatetraenoyl)-glycerol = 1-(5Z,8Z,11Z,14Z-eicosatetraenoyl)-2-(9Z-octadecenoyl)-glycerol + CoA hexadecane-1,2-diol + hexadecanoyl-CoA = 2-hydroxyhexadecyl hexadecanoate + CoA (9Z)-octadecenoyl-CoA + 1-decanoylglycerol = 1-decanoyl-2-(9Z-octadecenoyl)-glycerol + CoA (9Z)-octadecenoyl-CoA + 1-O-(9Z-octadecenyl)-glycerol = 1-O-(9Z-octadecenyl)-mono-(9Z-octadecenoyl)-glycerol + CoA (9Z)-octadecenoyl-CoA + 1,2-di-(9Z-octadecenoyl)-sn-glycerol = 1,2,3-tri-(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 Inhibited by oleic acid and sphingosine, while it is stimulated by phosphatidylcholine, phosphatidylserine and phosphatidic acid. Optimum pH is 7.0. Glycerolipid metabolism; triacylglycerol biosynthesis. Mainly expressed in small intestine. Detected in the small intestine in a proximal-to-distal gradient that correlated with fat absorption pattern. Present not only in the villi, but also in the crypt regions of the small intestine, which suggests that expression occurs prior to the maturation of enterocytes. Not detectable in other sections of the digestive tract, including stomach, cecum, colon and rectum, or other tissues such as kidney, liver and adipocytes (at protein level). Also detected in kidney, adipose and stomach. Expressed at very low level in liver, skeletal muscle and spleen. Not expressed in brain, heart, lung, skin, testis and thymus. Up-regulated in mice fed a high fat diet, implicating a role in diet-induced obesity (at protein level). Belongs to the diacylglycerol acyltransferase family.