All families / PF05251
PF05251: Ost5
Oligosaccharyltransferase subunit 5
- Curation status
- SEEDED
- Seed status
- EX DUF
- Characterization
- UNSCORED
Grounding
PF05251: Oligosaccharyltransferase subunit 5
IPR007915: integrated entry for Oligosaccharyltransferase subunit 5
Source description
Eukaryotic N-glycosylation is catalysed in the ER lumen, where the enzyme oligosaccharyltransferase (OTase) transfers donor glycans from a dolichol pyrophosphate (DolP) carrier (Lipid-linked oligosaccharide; LLO) to polypeptides. The yeast OTase is a hetero-oligomeric complex composed of essential (Ost1, Ost2, Wbp1, Stt3, and Swp1) and nonessential (Ost3, Ost4, Ost5, and Ost6) subunits. This domain family is found in Ost5, Q92316 (UniProtKB protein). The precise function of this subunit is not known, however Ost5 appears to form a sub-complex with Ost1, and this sub-complex associates with the catalytic Stt3 subunit of OTase. Down regulation of Ost5 resulted in a limited effect on glycosylation and no effect on the stability of Ost1 or Stt3 subunits [InterPro reference PUB00109240,InterPro reference PUB00109241].
Evidence and references
- InterPro entry and its literature references. PUB identifiers are internal InterPro references, not PubMed identifiers. Unresolved citations link to the originating entry.
- Frozen description source: InterPro/Pfam API
Source descriptions and links are provenance, not independent functional validation.
Evidence counts: not scored.
Curated functional assertions
No curated functional assertions supplied.
Protein sequence examples
5 verified sequence examples. FASTA
| UniProt | Protein / organism | Sequence | Provenance |
|---|---|---|---|
| P61165 | Dolichyl-diphosphooligosaccharide--protein glycosyltransferase subunit TMEM258 Homo sapiens | 79 aa; version 1 UniProt 2026_03 | PTM REGISTRY MIRROR |
| P61166 | Dolichyl-diphosphooligosaccharide--protein glycosyltransferase subunit TMEM258 Mus musculus | 79 aa; version 1 UniProt 2026_03 | UNIPROT FETCH |
| Q92316 | Dolichyl-diphosphooligosaccharide--protein glycosyltransferase subunit OST5 Saccharomyces cerevisiae (strain ATCC 204508 / S288c) | 86 aa; version 2 UniProt 2026_03 | UNIPROT FETCH1 sibling references |
| Q965T1 | Dolichyl-diphosphooligosaccharide--protein glycosyltransferase subunit TMEM258 Caenorhabditis elegans | 79 aa; version 1 UniProt 2026_03 | UNIPROT FETCH2 sibling references |
| Q9VVA8 | Transmembrane protein 258 Drosophila melanogaster | 78 aa; version 1 UniProt 2026_03 | UNIPROT FETCH |
Pfam membership is not functional evidence. Whole-protein sequences do not establish domain boundaries. A coverage gap here is not absence from UniProt.
Sequences and metadata: UniProt Consortium, CC BY 4.0.
Domain matches
No residue-level domain match evidence is available in this build. Structure and AlphaFold counters do not supply coordinates or establish function.
Snapshot counters
- proteins
- 3,042
- matches
- 3,052
- proteomes
- 2,536
- taxa
- 7,096
- structures
- 12
- alphafold models
- 2,628
- domain architectures
- 59
Classification basis
pfam previous unknown name
No scoring reasons supplied.
Related Mech records
This family joined the worklist after the frozen cross-Mech scan, so other Mechs were not searched for it. Missing links here are not evidence that other Mechs lack it; rows shown come from mentions of a former DUF/UPF name.
No cross-Mech examples are present in the supplied snapshot.
Curation history and reviews
No retained curation events supplied.
No retained review supplied.
Record source
Status and evidence
- Seed status
- A name-based classification of frozen InterPro/Pfam metadata. UNKNOWN CANDIDATE means the metadata explicitly says the function is unknown. KNOWN HISTORICAL DUF means a DUF name matched without that wording; this heuristic is not proof of a known function and does not establish experimental characterization. EX DUF means Pfam renamed the family away from a DUF/UPF name, as recorded in Pfam's previous identifiers; a rename usually follows published work on some members but is naming history, not proof of function for every member. Some EX DUF families' current names or descriptions still say the function is unknown; their classification basis lists this, and scoring does not treat them as characterized. FALSE POSITIVE TEXT HIT means the naming rules did not match.
- Characterization
- A separate evidence-scoring result. UNSCORED means no score has been calculated; it is not evidence that the family lacks a known function. Missing scores are not negative evidence. PARTIALLY CHARACTERIZED has partial support; KNOWN HISTORICAL DUF can inherit the seed label or reflect a known-function signal. Neither label implies experimental validation.
- Evidence counts
- Source-specific signals, not unique proteins, publications, or confidence scores. Known counts Rhea reactions and experimentally supported GO molecular-function annotations. Partial counts functional/domain assignments. Context counts structural, environmental, orthology, interaction and neighborhood signals; context alone does not assign function. Repeated annotations may not be independent.
- Curation status
- Reported separately from seed classification and characterization. SNAPSHOT ONLY means no curated metadata was supplied for this build. SEEDED denotes a source-derived record, not an expert-reviewed functional claim.
- Missing counts
- Not available means the source did not supply that counter. A zero is a reported count. Not scored means evidence counts are unavailable.