ALG3/YBL082C Summary Help

Standard Name ALG3 1
Systematic Name YBL082C
Alias RHK1 2
Feature Type ORF, Verified
Description Dolichol-P-Man dependent alpha(1-3) mannosyltransferase; involved in the synthesis of dolichol-linked oligosaccharide donor for N-linked glycosylation of proteins (2, 3, 4 and see Summary Paragraph)
Name Description Asparagine Linked Glycosylation 1
Chromosomal Location
ChrII:71127 to 69751 | ORF Map | GBrowse
Note: this feature is encoded on the Crick strand.
Gene Ontology Annotations All ALG3 GO evidence and references
  View Computational GO annotations for ALG3
Molecular Function
Manually curated
Biological Process
Manually curated
Cellular Component
Manually curated
Regulators 5 genes
Classical genetics
Large-scale survey
153 total interaction(s) for 86 unique genes/features.
Physical Interactions
  • Affinity Capture-MS: 2

Genetic Interactions
  • Negative Genetic: 86
  • Phenotypic Enhancement: 7
  • Phenotypic Suppression: 34
  • Positive Genetic: 18
  • Synthetic Growth Defect: 4
  • Synthetic Lethality: 2

Expression Summary
Length (a.a.) 458
Molecular Weight (Da) 52,860
Isoelectric Point (pI) 9.29
Phosphorylation PhosphoGRID | PhosphoPep Database
sequence information
ChrII:71127 to 69751 | ORF Map | GBrowse
Note: this feature is encoded on the Crick strand.
Last Update Coordinates: 2011-02-03 | Sequence: 1997-01-28
Subfeature details
Most Recent Updates
Coordinates Sequence
CDS 1..1377 71127..69751 2011-02-03 1997-01-28
Retrieve sequences
Analyze Sequence
S288C only
S288C vs. other species
S288C vs. other strains
External Links All Associated Seq | E.C. | Entrez Gene | Entrez RefSeq Protein | MIPS | Search all NCBI (Entrez) | UniProtKB
Primary SGDIDS000000178

During N-linked glycosylation of proteins, oligosaccharide chains are assembled on the carrier molecule dolichyl pyrophosphate in the following order: 2 molecules of N-acetylglucosamine (GlcNAc), 9 molecules of mannose, and 3 molecules of glucose. These 14-residue oligosaccharide cores are then transferred to asparagine residues on nascent polypeptide chains in the endoplasmic reticulum (ER). As proteins progress through the Golgi apparatus, the oligosaccharide cores are modified by trimming and extension to generate a diverse array of glycosylated proteins (reviewed in 5, 6).

Alg3p is an alpha 1,3 mannosyltransferase that catalyzes the addition of the sixth mannose moiety to the growing lipid-linked oligosaccharide (LLO) (3, 4). This is the first sugar added to the LLO in the lumen of the endoplasmic reticulum. The seventh mannose moiety is added by Alg9p. Disruption of ALG3 causes accumulation of lipid-linked oligosaccharides with five mannose residues (1, 3, 4).

The designation RHK1 indicates that mutants are resistant to the HM-1 killer toxin from the yeast Hansenula mrakii, possibly due to defective glycosylation of the toxin receptor (2).

Human ALG3 (OMIM) cDNA complements deletion of ALG3 in mutant yeast (7) and has been found to be mutated in the congenital disorder of glycosylation CDG-Id (OMIM) (7).

Last updated: 2005-07-01 Contact SGD

References cited on this page View Complete Literature Guide for ALG3
1) Huffaker TC and Robbins PW  (1983) Yeast mutants deficient in protein glycosylation. Proc Natl Acad Sci U S A 80(24):7466-70
2) Kimura T, et al.  (1997) A novel yeast gene, RHK1, is involved in the synthesis of the cell wall receptor for the HM-1 killer toxin that inhibits beta-1,3-glucan synthesis. Mol Gen Genet 254(2):139-47
3) Aebi M, et al.  (1996) Cloning and characterization of the ALG3 gene of Saccharomyces cerevisiae. Glycobiology 6(4):439-44
4) Sharma CB, et al.  (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
5) Herscovics A and Orlean P  (1993) Glycoprotein biosynthesis in yeast. FASEB J 7(6):540-50
6) Burda P and Aebi M  (1999) The dolichol pathway of N-linked glycosylation. Biochim Biophys Acta 1426(2):239-57
7) Korner C, et al.  (1999) Carbohydrate deficient glycoprotein syndrome type IV: deficiency of dolichyl-P-Man:Man(5)GlcNAc(2)-PP-dolichyl mannosyltransferase. EMBO J 18(23):6816-22