Involved in protein N-glycosylation. Essential for the second step of the dolichol-linked oligosaccharide pathway. N-acetyl-alpha-D-glucosaminyl-diphosphodolichol + UDP-N-acetyl-alpha-D-glucosamine = H(+) + N,N'-diacetylchitobiosyl diphosphodolichol + UDP Heterodimer with ALG14 to form a functional enzyme. Present with 1950 molecules/cell in log phase SD medium. Belongs to the glycosyltransferase 28 family.