MetaCyc Enzyme: Dol-P-Man:Man5GlcNAc2-PP-Dol mannosyltransferase

Gene: ALG3 Accession Number: G-5581 (MetaCyc)

Synonyms: RHK1

Species: Saccharomyces cerevisiae

Sequence analysis of the ALG3 protein product suggested a transmembrane protein containing 10 potential transmembrane helices. Endoplasmic reticulum location was suggested by the C-terminal sequence motif KKLN [Aebi96].
ALG3 mutants accumulate (mannosyl)5-(N-acetylglucosaminyl)2-diphosphodolichol [Huffaker83, Verostek91].

Citations: [Sharma01]

Gene Citations: [Sharma01]

Locations: endoplasmic reticulum

Map Position: [69,748 <- 71,124]

Molecular Weight of Polypeptide: 53.4 kD (from nucleotide sequence)

Unification Links: DIP:DIP-4854N , Entrez-gene:852196 , Mint:MINT-489474 , ModBase:P38179 , Protein Model Portal:P38179 , String:4932.YBL082C , Swiss-Model:P38179 , UniProt:P38179

Relationship Links: CAZy:IN-FAMILY:GT58 , InterPro:IN-FAMILY:IPR007873 , Panther:IN-FAMILY:PTHR12646 , Pfam:IN-FAMILY:PF05208

Gene-Reaction Schematic: ?

Gene-Reaction Schematic

GO Terms:

Cellular Component: GO:0005783 - endoplasmic reticulum [Aebi96]

Enzymatic reaction of: Dol-P-Man:Man5GlcNAc2-PP-Dol mannosyltransferase

EC Number:

a (mannosyl)5-(N-acetylglucosaminyl)2-diphosphodolichol[rough endoplasmic reticulum lumen] + a dolichyl β-D-mannosyl phosphate[rough endoplasmic reticulum lumen] <=> a (mannosyl)6-(N-acetylglucosaminyl)2-diphosphodolichol[rough endoplasmic reticulum lumen] + a dolichyl phosphate[rough endoplasmic reticulum lumen] + H+[rough endoplasmic reticulum lumen]

The reaction direction shown, that is, A + B ↔ C + D versus C + D ↔ A + B, is in accordance with the Enzyme Commission system.

The reaction is favored in the direction shown.

In Pathways: protein N-glycosylation (eukaryotic, high mannose)

ALG3 mutants accumulated (mannosyl)5-(N-acetylglucosaminyl)2-diphosphodolichol [Huffaker83, Verostek91]. Mannosyl transfer specifically to (mannosyl)5-(N-acetylglucosaminyl)2-diphosphodolichol by this enzyme was shown. This reaction was shown to be independent of divalent cations. After immunoprecipitation of the ALG3 protein, it was shown to exclusively catalyze the conversion of (mannosyl)5-(N-acetylglucosaminyl)2-diphosphodolichol to (mannosyl)6-(N-acetylglucosaminyl)2-diphosphodolichol [Sharma01].


Aebi96: Aebi M, Gassenhuber J, Domdey H, te Heesen S (1996). "Cloning and characterization of the ALG3 gene of Saccharomyces cerevisiae." Glycobiology 6(4);439-44. PMID: 8842708

Huffaker83: Huffaker TC, Robbins PW (1983). "Yeast mutants deficient in protein glycosylation." Proc Natl Acad Sci U S A 80(24);7466-70. PMID: 6369318

Sharma01: Sharma CB, Knauer R, Lehle L (2001). "Biosynthesis of lipid-linked oligosaccharides in yeast: the ALG3 gene encodes the Dol-P-Man:Man5GlcNAc2-PP-Dol mannosyltransferase." Biol Chem 382(2);321-8. PMID: 11308030

Verostek91: Verostek MF, Atkinson PH, Trimble RB (1991). "Structure of Saccharomyces cerevisiae alg3, sec18 mutant oligosaccharides." J Biol Chem 266(9);5547-51. PMID: 2005096

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Please cite the following article in publications resulting from the use of MetaCyc: Caspi et al, Nucleic Acids Research 42:D459-D471 2014
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