ALG3 Gene (Alpha-1,3-Mannosyltransferase)
ALG3: Congenital Disorder of Glycosylation, Type Id
Gene Information Card
| Symbol | ALG3 |
|---|---|
| Full Name | Alpha-1,3-Mannosyltransferase |
| Gene Type | Protein coding |
| Chromosomal Location | 3q27.1 |
| NCBI Gene ID | 10195 ncbi.nlm.nih.gov/gene/10195 |
| Ensembl ID | ENSG00000134460 |
| UniProt ID | Q92685 |
| OMIM ID | 608750 |
| HGNC ID | 23056 |
| Aliases | CDG1D, DKFZp686F2269, NOT56L, ALG3 mannosyltransferase |
Description
The ALG3 gene encodes alpha-1,3-mannosyltransferase, an enzyme localized to the endoplasmic reticulum that catalyzes the addition of the first mannose residue to the dolichol-linked oligosaccharide precursor Man5GlcNAc2-PP-dolichol, forming Man6GlcNAc2-PP-dolichol. This step is critical for the biosynthesis of N-linked glycoproteins. Mutations in ALG3 cause congenital disorder of glycosylation type Id (CDG-Id), characterized by severe neurological impairment, dysmorphic features, and coagulopathy.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| Congenital disorder of glycosylation type Id (CDG-Id) | Loss-of-function mutations in ALG3 impair N-glycan assembly, leading to hypoglycosylation of multiple proteins. | ClinVar, OMIM |
| ALG3-related disorder | Biallelic pathogenic variants cause a spectrum of glycosylation defects with variable severity. | NCBI Gene, OMIM |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Liver | 8.2 | Low |
| Brain | 6.5 | Low |
| Heart | 5.1 | Low |
| Kidney | 7.0 | Low |
| Testis | 9.8 | Low |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| HEK293 | 10.3 | Moderate expression |
| HeLa | 7.8 | Low expression |
| K562 | 6.1 | Low expression |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| c.512G>A (p.Arg171His) | Missense | Rare | Loss of function; associated with CDG-Id |
| c.1A>G (p.Met1Val) | Start loss | Rare | Loss of function; severe CDG-Id |
| c.1042C>T (p.Arg348*) | Nonsense | Rare | Loss of function; truncated protein |
Mutation functional classification
Loss of Function (LOF)
Most ALG3 mutations are loss-of-function, reducing or abolishing mannosyltransferase activity, leading to incomplete N-glycan precursor assembly.
Gain of Function (GOF)
No gain-of-function mutations reported.
Dominant Negative (DN)
No dominant-negative mutations reported.
View complete mutation data：
Gene Ontology (GO)
| • GO:0004576 - oligosaccharyl transferase activity | • GO:0006487 - protein N-linked glycosylation |
| • GO:0005789 - endoplasmic reticulum membrane | • GO:0016757 - transferase activity |
| • transferring glycosyl groups | • GO:0006490 - oligosaccharide-lipid intermediate assembly |
Pathways
• N-glycan biosynthesis (KEGG: hsa00510)
• Metabolism of proteins (Reactome: R-HSA-392499)
Protein Summary
The ALG3 protein (UniProt Q92685) is a 441-amino acid transmembrane protein located in the endoplasmic reticulum membrane. It functions as a dolichyl-phosphate-mannose-dependent alpha-1,3-mannosyltransferase, adding the first mannose to the Man5GlcNAc2-PP-dolichol intermediate. This activity is essential for the proper assembly of the lipid-linked oligosaccharide precursor used in N-glycosylation. Deficiency leads to accumulation of truncated oligosaccharides and hypoglycosylation of secretory and membrane proteins.
Related Services
Related Products
| Product name | Cat.No. | Species | Gene ID | |
|---|---|---|---|---|
| ALG3 Knockout HEK293 Cell Line | EDJ-KQ6943 | Human | 10195 | Details Get a Quote |
| ALG3 Knockout A-549 Cell Line | EDJ-KQ31600 | Human | 10195 | Details Get a Quote |
| ALG3 Knockout HCT 116 Cell Line | EDJ-KQ31601 | Human | 10195 | Details Get a Quote |
| ALG3 Knockout HeLa Cell Line | EDJ-KQ31602 | Human | 10195 | Details Get a Quote |
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