The formation of N-glycosidic linkages of glycoproteins involves the ordered assembly of the common Glc3Man9GlcNAc2 core-oligosaccharide on the lipid carrier dolichyl pyrophosphate. Whereas early mannosylation steps occur on the cytoplasmic side of the endoplasmic reticulum with GDP-Man as donor, the final reactions from Man5GlcNAc2-PP-Dol to Man9GlcNAc2-PP-Dol on the lumenal side use Dol-P-Man [3]. ALG3 gene encodes the Dol-P-Man:Man5GlcNAc2-PP-Dol mannosyltransferase.

1: Carbohydrate deficient glycoprotein syndrome type IV: deficiency of dolichyl-P-Man:Man(5)GlcNAc(2)-PP-dolichyl mannosyltransferase. Korner C, Knauer R, Stephani U, Marquardt T, Lehle L, von Figura K; EMBO J 1999;18:6816-6822. PMID:10581255

2: Cloning and characterization of the ALG3 gene of Saccharomyces cerevisiae. Aebi M, Gassenhuber J, Domdey H, te Heesen S; Glycobiology 1996;6:439-444. PMID:8842708

3: Biosynthesis of lipid-linked oligosaccharides in yeast: the ALG3 gene encodes the Dol-P-Man:Man5GlcNAc2-PP-Dol mannosyltransferase. Sharma CB, Knauer R, Lehle L; Biol Chem 2001;382:321-328. PMID:11308030