Glucosyltransferase involved in the biosynthesis of the non-bilayer-forming membrane lipid beta-monoglucosyldiacylglycerol which contributes to regulate the properties and stability of the membrane. Catalyzes the transfer of a glucosyl residue from UDP-Glc to diacylglycerol (DAG) acceptor to form the corresponding beta-glucosyl-DAG (1,2-diacyl-3-O-(beta-D-glucopyranosyl)-sn-glycerol). It can only use UDP-Glc as sugar donor. Two types of DAG (dipalmitoyl-DAG (DPDAG) and 1-oleoyl-2-palmitoyl-DAG (OPDAG)) can be used as sugar acceptors, but OPDAG is preferred. a 1,2-diacyl-sn-glycerol + UDP-alpha-D-glucose = a 1,2-diacyl-3-O-(beta-D-glucopyranosyl)-sn-glycerol + H(+) + UDP Belongs to the glycosyltransferase 2 family.