ALG9: Alpha-1,2-Mannosyltransferase Gene
Key player in N-glycosylation and congenital disorders of glycosylation
Gene Information Card
| Symbol | ALG9 |
|---|---|
| Full Name | Alpha-1,2-Mannosyltransferase |
| Gene Type | Protein coding |
| Chromosomal Location | 11q23.1 |
| NCBI Gene ID | 79796 ncbi.nlm.nih.gov/gene/79796 |
| Ensembl ID | ENSG00000149131 |
| UniProt ID | Q9H6U8 |
| OMIM ID | 606941 |
| HGNC ID | 15672 |
| Aliases | DIBD1, ALG9 mannosyltransferase, CDG-IL, DHDDS2 |
Description
The ALG9 gene encodes alpha-1,2-mannosyltransferase, an enzyme involved in the N-glycosylation pathway. It catalyzes the addition of mannose residues to the lipid-linked oligosaccharide precursor in the endoplasmic reticulum. Mutations in ALG9 cause congenital disorder of glycosylation type IL (CDG-IL), a multisystem disorder characterized by developmental delay, hypotonia, and variable neurological involvement.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| Congenital disorder of glycosylation type IL (CDG-IL) | Loss-of-function mutations in ALG9 impair N-glycan assembly, leading to underglycosylation of proteins | OMIM #608776; ClinVar |
| Polycystic kidney disease (PKD) modifier | ALG9 variants may influence cystogenesis in PKD patients | PMID: 26979962 |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Liver | 12.5 | Medium |
| Kidney | 10.2 | Medium |
| Brain | 8.9 | Medium |
| Heart | 7.1 | Low |
| Lung | 6.3 | Low |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| HEK293 | 15.4 | High expression in embryonic kidney cells |
| HeLa | 11.2 | Moderate expression in cervical cancer cells |
| HepG2 | 13.8 | High expression in liver cancer cells |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| c.1160A>G (p.Tyr387Cys) | Missense | Rare | Reduced enzyme activity; associated with CDG-IL |
| c.1462C>T (p.Arg488Trp) | Missense | Rare | Loss of function; reported in CDG-IL patients |
| c.1A>G (p.Met1Val) | Start loss | Rare | Complete loss of protein; severe CDG-IL phenotype |
Mutation functional classification
Loss of Function (LOF)
Most ALG9 mutations are loss-of-function, impairing mannosyltransferase activity and N-glycosylation.
Gain of Function (GOF)
No gain-of-function mutations reported.
Dominant Negative (DN)
Not described; disease is autosomal recessive.
View complete mutation data：
Gene Ontology (GO)
| • GO:0004576 - alpha-1 | • 2-mannosyltransferase activity |
| • GO:0006488 - dolichol-linked oligosaccharide biosynthetic process | • GO:0005789 - endoplasmic reticulum membrane |
| • GO:0016757 - transferase activity | • transferring glycosyl groups |
Pathways
• N-glycan biosynthesis (KEGG: hsa00510)
• Protein glycosylation in the endoplasmic reticulum (Reactome: R-HSA-446203)
Protein Summary
ALG9 encodes a 682-amino acid transmembrane protein localized to the endoplasmic reticulum. It functions as a dolichyl-phosphate-mannose-dependent alpha-1,2-mannosyltransferase, adding the seventh and ninth mannose residues to the lipid-linked oligosaccharide precursor. The protein is essential for proper N-glycosylation of secreted and membrane proteins.
Related Services
Related Products
| Product name | Cat.No. | Species | Gene ID | |
|---|---|---|---|---|
| ALG9 Knockout HEK293 Cell Line | EDJ-KQ51701 | Human | 79796 | Details Get a Quote |
| ALG9 Knockout HeLa Cell Line | EDJ-KQ57230 | Human | 79796 | Details Get a Quote |
| ALG9 Knockout A-549 Cell Line | EDJ-KQ65743 | Human | 79796 | Details Get a Quote |
| ALG9 Knockout HCT 116 Cell Line | EDJ-KQ74160 | Human | 79796 | Details Get a Quote |
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