The biosynthesis of asparagine-linked glycoproteins utilizes a dolichyl diphosphate-linked glycosyl donor, which is assembled by the series of membrane-bound glycosyltransferases that comprise the dolichol pathway. Alg2 mannosyltransferase from Saccharomyces cerevisiae carries out an ¦Á1,3-mannosylation (cf. EC 2.4.1.132) of D-Man-¦Â-(1¡ú4)-D-GlcNAc-¦Â-(1¡ú4)-GlcNAc-diphosphodolichol, followed by an ¦Á1,6-mannosylation, to form the first branched pentasaccharide intermediate of the dolichol pathway [1,2].
Cofactor
History
Reactions
GDP-D-mannose + D-Man-alpha-(1->3)-D-Man-beta-(1->4)-D-GlcNAc-beta- (1->4)-D-GlcNAc-diphosphodolichol = Gdp + D-Man-alpha-(1->3)-(D-Man- alpha-(1->6))-D-Man-beta-(1->4)-D-GlcNAc-beta-(1->4)-D-GlcNAc- diphosphodolichol.
