ALG6 (enzyme class) explained

Dolichyl-P-Glc:Man9GlcNAc2-PP-dolichol alpha-1,3-glucosyltransferase
Ec Number:	2.4.1.267

Dolichyl-P-Glc:Man9GlcNAc2-PP-dolichol alpha-1,3-glucosyltransferase (ALG6, Dol-P-Glc:Man9GlcNAc2-PP-Dol alpha-1,3-glucosyltransferase) is an enzyme with systematic name dolichyl beta-D-glucosyl 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->2)-D-Man-alpha-(1->6))-D-Man-alpha-(1->6))-D-Man-beta-(1->4)-D-GlcNAc-beta-(1->4)-D-GlcNAc-diphosphodolichol alpha-1,3-glucosyltransferase.^{[1] [2] [3]}

This enzyme catalyses the following chemical reaction

which is:

dolichyl beta-D-glucosyl 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->2)-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-Glc-alpha-(1->3)-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

See also

• EC 2.4.1.265 (Dol-P-Glc:Glc1Man9GlcNAc2-PP-Dol alpha-1,3-glucosyltransferase)
• EC 2.4.1.256 (Dol-P-Glc:Glc2Man9GlcNAc2-PP-Dol alpha-1,2-glucosyltransferase)

Notes and References

1. Reiss G, te Heesen S, Zimmerman J, Robbins PW, Aebi M . Isolation of the ALG6 locus of Saccharomyces cerevisiae required for glucosylation in the N-linked glycosylation pathway . Glycobiology . 6 . 5 . 493–8 . July 1996 . 8877369 . 10.1093/glycob/6.5.493 . free . 20.500.11850/422718 . free .
2. Runge KW, Huffaker TC, Robbins PW . Two yeast mutations in glucosylation steps of the asparagine glycosylation pathway . The Journal of Biological Chemistry . 259 . 1 . 412–7 . January 1984 . 6423630 .
3. Westphal V, Xiao M, Kwok PY, Freeze HH . Identification of a frequent variant in ALG6, the cause of Congenital Disorder of Glycosylation-Ic . Human Mutation . 22 . 5 . 420–1 . November 2003 . 14517965 . 10.1002/humu.9195 .