a dolichyl phosphate + UDP-alpha-D-glucose = a dolichyl beta-D-glucosyl phosphate + UDP Protein modification; protein glycosylation. Its interaction with the substrate UDP-glucose may occur at the cytoplasmic side of the ER, whereas the steps utilizing dolichyl beta-D-glucosyl phosphate take place in the lumen of the ER. Belongs to the glycosyltransferase 2 family.