Dolichyl-phosphate beta-glucosyltransferase involved in the glycosylation of glycoproteins through the synthesis of dolichyl beta-D-glucosyl phosphate which serves as a sugar donor for transfer of three glucose residues to the Man-9-GlcNAc-2-PP-dolichol precursor to N-glycans. a dolichyl phosphate + UDP-alpha-D-glucose = a dolichyl beta-D-glucosyl phosphate + UDP Protein modification; protein glycosylation. Belongs to the glycosyltransferase 2 family.