TMEM258: Transmembrane Protein 258
A component of the oligosaccharyltransferase complex involved in N-glycosylation and linked to congenital disorders of glycosylation.
Gene Information Card
| Symbol | TMEM258 |
|---|---|
| Full Name | Transmembrane Protein 258 |
| Gene Type | Protein coding |
| Chromosomal Location | 11q23.3 |
| NCBI Gene ID | 11273 ncbi.nlm.nih.gov/gene/11273 |
| Ensembl ID | ENSG00000149269 |
| UniProt ID | Q96S66 |
| OMIM ID | 617614 |
| HGNC ID | 28476 |
| Aliases | C11orf2, DC11, HSPC085, MDS010, OST4 |
Description
TMEM258 encodes a transmembrane protein that is a subunit of the oligosaccharyltransferase (OST) complex. The OST complex catalyzes the transfer of a high-mannose oligosaccharide from a lipid carrier to asparagine residues on nascent polypeptides, a critical step in N-linked glycosylation. TMEM258 is essential for OST complex stability and function. Mutations in TMEM258 are associated with congenital disorders of glycosylation (CDG), characterized by multisystemic abnormalities.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| Congenital disorder of glycosylation (CDG) type I | Loss-of-function mutations in TMEM258 impair OST complex activity, leading to underglycosylation of proteins. | OMIM #617614; PMID: 27545680 |
| Intellectual disability | Associated with CDG; defective N-glycosylation affects neuronal development. | PMID: 27545680 |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Liver | 12.5 | Medium |
| Brain | 10.2 | Medium |
| Heart | 8.9 | Low |
| Kidney | 11.3 | Medium |
| Pancreas | 9.7 | Low |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| HEK293 | 15.4 | High expression |
| HeLa | 13.1 | Medium expression |
| K562 | 10.8 | Medium expression |
| HepG2 | 14.2 | High expression |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| c.1A>G (p.Met1?) | Missense | Rare | Loss of start codon, likely loss of function |
| c.2T>C (p.Met1?) | Missense | Rare | Loss of start codon, likely loss of function |
| c.3G>A (p.Met1?) | Missense | Rare | Loss of start codon, likely loss of function |
Mutation functional classification
Loss of Function (LOF)
Mutations affecting the start codon or introducing premature stop codons lead to loss of TMEM258 function, impairing OST complex assembly and N-glycosylation.
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)
| • N-linked glycosylation | • oligosaccharyltransferase complex |
| • endoplasmic reticulum membrane | • integral component of membrane |
| • protein glycosylation |
Pathways
• N-glycan biosynthesis (KEGG: hsa00510)
• Protein processing in endoplasmic reticulum (KEGG: hsa04141)
Protein Summary
TMEM258 is a small transmembrane protein (approximately 15 kDa) localized to the endoplasmic reticulum membrane. It is a subunit of the oligosaccharyltransferase (OST) complex, which is responsible for the transfer of oligosaccharides to asparagine residues of nascent proteins. TMEM258 is required for OST complex stability and efficient N-glycosylation. Loss of function leads to congenital disorders of glycosylation.
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