Dolichyl-P-Man:Man8GlcNAc2-PP-dolichol alpha-1,2-mannosyltransferase explained

Dolichyl-P-Man:Man8GlcNAc2-PP-dolichol alpha-1,2-mannosyltransferase
Ec Number:	2.4.1.261

Dolichyl-P-Man:Man8GlcNAc2-PP-dolichol alpha-1,2-mannosyltransferase (ALG9, ALG9 alpha1,2 mannosyltransferase, dolichylphosphomannose-dependent ALG9 mannosyltransferase, ALG9 mannosyltransferase, Dol-P-Man:Man8GlcNAc2-PP-Dol alpha-1,2-mannosyltransferase) is an enzyme with systematic name dolichyl beta-D-mannosyl phosphate:D-Man-alpha-(1->2)-D-Man-alpha-(1->2)-D-Man-alpha-(1->3)-(D-Man-alpha-(1->2)-D-Man-alpha-(1->3)-(D-Man-alpha-(1->6))-D-Man-alpha-(1->6))-D-Man-beta-(1->4)-D-GlcNAc-beta-(1->4)-D-GlcNAc-diphosphodolichol 2-alpha-D-mannosyltransferase.^{[1] [2]} This enzyme catalyses the following chemical reaction

dolichyl beta-D-mannosyl phosphate + D-Man-alpha-(1->2)-D-Man-alpha-(1->2)-D-Man-alpha-(1->3)-[D-Man-alpha-(1->2)-D-Man-alpha-(1->3)-[D-Man-alpha-(1->6)]-D-Man-alpha-(1->6)]-D-Man-beta-(1->4)-D-GlcNAc-beta-(1->4)-D-GlcNAc-diphosphodolichol

\rightleftharpoons D-Man-alpha-(1->2)-D-Man-alpha-(1->2)-D-Man-alpha-(1->3)-[D-Man-alpha-(1->2)-D-Man-alpha-(1->3)-[D-Man-alpha-(1->2)-D-Man-alpha-(1->6)]-D-Man-alpha-(1->6)]-D-Man-beta-(1->4)-D-GlcNAc-beta-(1->4)-D-GlcNAc-diphosphodolichol + dolichyl phosphate

The formation of N-glycosidic linkages of glycoproteins involves the ordered assembly of the common Glc3Man9GlcNAc2 core-oligosaccharide on the lipid carrier dolichyl diphosphate.

Notes and References

1. Vleugels W, Keldermans L, Jaeken J, Butters TD, Michalski JC, Matthijs G, Foulquier F . Quality control of glycoproteins bearing truncated glycans in an ALG9-defective (CDG-IL) patient . Glycobiology . 19 . 8 . 910–7 . August 2009 . 19451548 . 10.1093/glycob/cwp067 .
2. Frank CG, Aebi M . ALG9 mannosyltransferase is involved in two different steps of lipid-linked oligosaccharide biosynthesis . Glycobiology . 15 . 11 . 1156–63 . November 2005 . 15987956 . 10.1093/glycob/cwj002 . free . 20.500.11850/31140 . free .