N-linked (asparagine-linked) glycosylation of proteins is mediated by a highly conserved pathway in eukaryotes, in which a lipid (dolicholphosphate)-linked oligosaccharide is assembled at the endoplasmic reticulum membrane prior to the transfer of the oligosaccharide moiety to the target asparagine residues. This oligosaccharide is composed of Glc(3)Man(9)GlcNAc(2). The addition of the three glucose residues is the final series of steps in the synthesis of the oligosaccharide precursor. Dolichyl pyrophosphate Glc1Man9GlcNAc2 alpha-1,3-glucosyltransferase (ALG8) transfers the second glucose residue [].Mutations of theALG8 gene cause congenital disorder of glycosylation 1H (CDG1H)1 [].
N-linked (asparagine-linked) glycosylation of proteins is mediated by a highly conserved pathway in eukaryotes, in which a lipid (dolicholphosphate)-linked oligosaccharide is assembled at the endoplasmic reticulum membrane prior to the transfer of the oligosaccharidemoiety to the target asparagine residues. This oligosaccharide is composed of Glc(3)Man(9)GlcNAc(2). The addition of the threeglucose residues is the final series of steps in the synthesis of the oligosaccharide precursor. Alg6 transfers the first glucose residue,and Alg8 transfers the second one []. In the human alg6 gene, a C-T transition, which causes Ala333 to be replaced with Val, hasbeen identified as the cause of a congenital disorder of glycosylation, designated as type Ic OMIM:603147 [].
