Chitobiosyldiphosphodolichol beta-mannosyltransferase is an enzyme that is encoded by the ALG1 gene whose structure and function has been conserved from yeast to man.
The biosynthesis of lipid-linked oligosaccharides is highly conserved among eukaryotes and is catalyzed by 14 glycosyltransferases in an ordered stepwise manner. The Alg1 mannosyltransferase I (MT I) catalyzes the first mannosylation step in this process.