ALG9/YNL219C Summary Help

Standard Name ALG9 1
Systematic Name YNL219C
Feature Type ORF, Verified
Description Mannosyltransferase, involved in N-linked glycosylation; catalyzes both the transfer of seventh mannose residue on B-arm and ninth mannose residue on the C-arm from Dol-P-Man to lipid-linked oligosaccharides; mutation of the human ortholog causes type 1 congenital disorders of glycosylation (1, 2, 3 and see Summary Paragraph)
Name Description Asparagine-Linked Glycosylation 4
Chromosomal Location
ChrXIV:237663 to 235996 | ORF Map | GBrowse
Note: this feature is encoded on the Crick strand.
Gene Ontology Annotations All ALG9 GO evidence and references
  View Computational GO annotations for ALG9
Molecular Function
Manually curated
Biological Process
Manually curated
Cellular Component
Manually curated
Regulators 4 genes
Classical genetics
Large-scale survey
315 total interaction(s) for 222 unique genes/features.
Physical Interactions
  • Affinity Capture-MS: 3
  • Affinity Capture-RNA: 1
  • Co-purification: 1
  • Reconstituted Complex: 1
  • Two-hybrid: 6

Genetic Interactions
  • Dosage Growth Defect: 1
  • Negative Genetic: 232
  • Phenotypic Enhancement: 2
  • Phenotypic Suppression: 42
  • Positive Genetic: 22
  • Synthetic Growth Defect: 1
  • Synthetic Lethality: 3

Expression Summary
Length (a.a.) 555
Molecular Weight (Da) 63,776
Isoelectric Point (pI) 8.74
Phosphorylation PhosphoGRID | PhosphoPep Database
sequence information
ChrXIV:237663 to 235996 | ORF Map | GBrowse
Note: this feature is encoded on the Crick strand.
Last Update Coordinates: 2011-02-03 | Sequence: 1996-07-31
Subfeature details
Most Recent Updates
Coordinates Sequence
CDS 1..1668 237663..235996 2011-02-03 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 SGDIDS000005163

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).

Alg9p, which is an alpha 1,2 mannosyltransferase, catalyzes two steps in lipid-linked oligosaccharide (LLO) assembly: the addition of the seventh and ninth mannose moieties to the growing oligosaccharide (1, 2) in the lumen of the endoplasmic reticulum. The sixth and eighth mannose moieties are added by Alg3p and Alg12p, respectively. Disruption of ALG9 causes accumulation of lipid-linked oligosaccharides with six mannose residues and hypoglycosylation of secreted proteins (1).

Human ALG9 (OMIM) cDNA complements the deletion of yeast ALG9 in a delta-alg9 wbp1-2 background (2) and has been found to be mutated in the congenital disorder of glycosylation CDG-1L (OMIM).

Last updated: 2005-07-12 Contact SGD

References cited on this page View Complete Literature Guide for ALG9
1) Burda P, et al.  (1996) Stepwise assembly of the lipid-linked oligosaccharide in the endoplasmic reticulum of Saccharomyces cerevisiae: identification of the ALG9 gene encoding a putative mannosyl transferase. Proc Natl Acad Sci U S A 93(14):7160-5
2) Frank CG, et al.  (2004) Identification and functional analysis of a defect in the human ALG9 gene: definition of congenital disorder of glycosylation type IL. Am J Hum Genet 75(1):146-50
3) Frank CG and Aebi M  (2005) ALG9 mannosyltransferase is involved in two different steps of lipid-linked oligosaccharide biosynthesis. Glycobiology 15(11):1156-63
4) Huffaker TC and Robbins PW  (1982) Temperature-sensitive yeast mutants deficient in asparagine-linked glycosylation. J Biol Chem 257(6):3203-10
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