FUNCTION Part of the UDP-N-acetylglucosamine transferase complex that operates in the biosynthetic pathway of dolichol-linked oligosaccharides, the glycan precursors employed in protein asparagine (N)-glycosylation. The assembly of dolichol-linked oligosaccharides begins on the cytosolic side of the endoplasmic reticulum membrane and finishes in its lumen. The sequential addition of sugars to dolichol pyrophosphate produces dolichol-linked oligosaccharides containing fourteen sugars, including two GlcNAcs, nine mannoses and three glucoses. Once assembled, the oligosaccharides are transferred from the lipid to nascent proteins by oligosaccharyltransferases. Functions as a protein-membrane adapter recruiting ALG13 at the cytoplasmic face of the endoplasmic reticulum, where the complex catalyzes the second step of dolichol pyrophosphate biosynthesis, transferring a beta1,4-linked N-acetylglucosamine (GlcNAc) from UDP-GlcNAc to GlcNAc-pyrophosphatedolichol (Gn-PDol) to produce N,N'-diacetylchitobiosyl diphosphodolichol. N,N'-diacetylchitobiosyl diphosphodolichol is a substrate for ALG1, the following enzyme in the biosynthetic pathway.SUBUNIT Forms with ALG13 the active heterodimeric UDP-N-acetylglucosamine transferase complex.SUBCELLULAR LOCATION The disease is caused by variants affecting the gene represented in this entry.DISEASE The disease may be caused by variants affecting the gene represented in this entry.DISEASE The disease may be caused by variants affecting the gene represented in this entry.SIMILARITY Belongs to the ALG14 family.