All families / PF02754
PF02754: CCG
Cysteine-rich domain
- Curation status
- SEEDED
- Seed status
- EX DUF
- Characterization
- UNSCORED
Grounding
PF02754: Cysteine-rich domain
IPR004017: integrated entry for Cysteine-rich domain
Source description
The key element of this domain is the CX31-38CCX33-34CXXC sequence motif normally found at the C-terminus in archaeal and bacterial Hdr-like proteins [InterPro reference PUB00109129]. There may be one or two copies, and the motif is probably an iron-sulfur binding cluster. In some instances one of the cysteines is replaced by an aspartate, and aspartate can in principle also function as a ligand of an iron-sulfur cluster [InterPro reference PUB00109129]. The entry includes a subunit from heterodisulphide reductase and a subunit from glycolate oxidase (P52074 (UniProtKB protein)) [InterPro reference PUB00007282] and glycerol-3-phosphate dehydrogenase.
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
11 verified sequence examples. FASTA
| UniProt | Protein / organism | Sequence | Provenance |
|---|---|---|---|
| D9PUX5 | Fumarate reductase (CoM/CoB) subunit B Methanothermobacter marburgensis (strain ATCC BAA-927 / DSM 2133 / JCM 14651 / NBRC 100331 / OCM 82 / Marburg) | 489 aa; version 1 UniProt 2026_03 | UNIPROT FETCH2 sibling references |
| O07020 | Lactate utilization protein A Bacillus subtilis (strain 168) | 238 aa; version 1 UniProt 2026_03 | UNIPROT FETCH1 sibling references |
| P0A996 | Anaerobic glycerol-3-phosphate dehydrogenase subunit C Escherichia coli (strain K12) | 396 aa; version 1 UniProt 2026_03 | PTM REGISTRY MIRROR11 sibling references
|
| P45866 | Probable iron-sulfur-binding oxidoreductase FadF Bacillus subtilis (strain 168) | 705 aa; version 1 UniProt 2026_03 | UNIPROT FETCH1 sibling references |
| P52074 | Glycolate oxidase iron-sulfur subunit Escherichia coli (strain K12) | 407 aa; version 1 UniProt 2026_03 | PTM REGISTRY MIRROR |
| P77252 | Uncharacterized protein YkgE Escherichia coli (strain K12) | 239 aa; version 1 UniProt 2026_03 | UNIPROT FETCH1 sibling references |
| P94534 | Probable glycolate oxidase iron-sulfur subunit Bacillus subtilis (strain 168) | 444 aa; version 1 UniProt 2026_03 | UNIPROT FETCH |
| Q1QYW0 | Probable membrane-anchored ferredoxin csal_0991 Chromohalobacter israelensis (strain ATCC BAA-138 / DSM 3043 / CIP 106854 / NCIMB 13768 / 1H11) | 670 aa; version 1 UniProt 2026_03 | UNIPROT FETCH1 sibling references |
| Q57557 | Uncharacterized iron-sulfur protein MJ0092 Methanocaldococcus jannaschii (strain ATCC 43067 / DSM 2661 / JAL-1 / JCM 10045 / NBRC 100440) | 489 aa; version 1 UniProt 2026_03 | PTM REGISTRY MIRROR1 sibling references |
| Q58153 | CoB--CoM heterodisulfide reductase subunit B 1 Methanocaldococcus jannaschii (strain ATCC 43067 / DSM 2661 / JAL-1 / JCM 10045 / NBRC 100440) | 294 aa; version 1 UniProt 2026_03 | PTM REGISTRY MIRROR |
First 10 shown; the FASTA and family JSON contain all examples.
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
- 37,412
- matches
- 67,945
- proteomes
- 14,229
- taxa
- 20,217
- structures
- 19
- alphafold models
- 23,792
- domain architectures
- 142
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.