ALG5/YPL227C Summary Help

Standard Name ALG5 1
Systematic Name YPL227C
Feature Type ORF, Verified
Description UDP-glucose:dolichyl-phosphate glucosyltransferase; involved in asparagine-linked glycosylation in the endoplasmic reticulum (2 and see Summary Paragraph)
Name Description Asparagine-Linked Glycosylation 3
Chromosomal Location
ChrXVI:121167 to 120163 | ORF Map | GBrowse
Note: this feature is encoded on the Crick strand.
Gene Ontology Annotations All ALG5 GO evidence and references
  View Computational GO annotations for ALG5
Molecular Function
Manually curated
Biological Process
Manually curated
Cellular Component
Manually curated
Regulators 6 genes
Classical genetics
Large-scale survey
261 total interaction(s) for 151 unique genes/features.
Physical Interactions
  • Affinity Capture-MS: 4
  • Co-purification: 1
  • PCA: 33

Genetic Interactions
  • Dosage Rescue: 1
  • Negative Genetic: 139
  • Phenotypic Enhancement: 8
  • Phenotypic Suppression: 29
  • Positive Genetic: 31
  • Synthetic Growth Defect: 6
  • Synthetic Lethality: 8
  • Synthetic Rescue: 1

Expression Summary
Length (a.a.) 334
Molecular Weight (Da) 38,346
Isoelectric Point (pI) 9.17
Phosphorylation PhosphoGRID | PhosphoPep Database
sequence information
ChrXVI:121167 to 120163 | ORF Map | GBrowse
Note: this feature is encoded on the Crick strand.
Last Update Coordinates: 1996-07-31 | Sequence: 1996-07-31
Subfeature details
Most Recent Updates
Coordinates Sequence
CDS 1..1005 121167..120163 1996-07-31 1996-07-31
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 SGDIDS000006148

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 4, 5).

Alg5p is a transmembrane (2) dolichyl-phosphate beta-glucosyltransferase that adds glucose to dolichyl-phosphate (Dol-P) on the cytoplasmic side of the endoplasmic reticulum (6). Dol-P then reverses orientation, flipping glucose into the lumen of the ER, where it serves as a source of glucose for growing lipid-linked oligosaccharides (LLO's). Mutants lacking ALG5 accumulate LLO's with nine mannose moieties (Man9)--but no glucose moieties--which are transferred to proteins with reduced efficiency (7); alg5 mutants have no apparent growth defect (7, 1). Dpm1p performs an analogous function for mannose, which is also transported into the ER via Dol-P.

Loss of either ALG5 or ALG6, which adds the first glucose moiety to LLO's, causes the accumulation of Man9 LLO's; this phenotype is shared with the human congenital disorder of glycosylation CDG-Ic (OMIM), which is due to mutations in hALG6 (OMIM), not hALG5 (OMIM). hALG5 and hALG6 appear to be coordinately expressed (8). Trichomonas vaginalis has several homologous copies of ALG5, but lacks a DPM1 homolog (9).

Last updated: 2005-07-01 Contact SGD

References cited on this page View Complete Literature Guide for ALG5
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) Heesen S, et al.  (1994) Isolation of the ALG5 locus encoding the UDP-glucose:dolichyl-phosphate glucosyltransferase from Saccharomyces cerevisiae. Eur J Biochem 224(1):71-9
3) Huffaker TC and Robbins PW  (1982) Temperature-sensitive yeast mutants deficient in asparagine-linked glycosylation. J Biol Chem 257(6):3203-10
4) Herscovics A and Orlean P  (1993) Glycoprotein biosynthesis in yeast. FASEB J 7(6):540-50
5) Burda P and Aebi M  (1999) The dolichol pathway of N-linked glycosylation. Biochim Biophys Acta 1426(2):239-57
6) Stagljar I, et al.  (1998) A genetic system based on split-ubiquitin for the analysis of interactions between membrane proteins in vivo. Proc Natl Acad Sci U S A 95(9):5187-92
7) Runge KW, et al.  (1984) Two yeast mutations in glucosylation steps of the asparagine glycosylation pathway. J Biol Chem 259(1):412-7
8) Imbach T, et al.  (1999) A mutation in the human ortholog of the Saccharomyces cerevisiae ALG6 gene causes carbohydrate-deficient glycoprotein syndrome type-Ic. Proc Natl Acad Sci U S A 96(12):6982-7
9) Samuelson J, et al.  (2005) The diversity of dolichol-linked precursors to Asn-linked glycans likely results from secondary loss of sets of glycosyltransferases. Proc Natl Acad Sci U S A 102(5):1548-53