All families / PF07254
PF07254: Cpta_toxin
Membrane-bound toxin component of toxin-antitoxin system
- Curation status
- SEEDED
- Seed status
- EX DUF
- Characterization
- UNSCORED
Grounding
PF07254: Membrane-bound toxin component of toxin-antitoxin system
IPR009883: integrated entry for Membrane-bound toxin component of toxin-antitoxin system
Source description
CptA is a family of bacterial proteins named for the member of this family, YGFX_ECOLI, Swissprot:Q46824. YgfX was previously thought to be the toxic part of a toxin-antitoxin module [InterPro reference PUB00075551] along with the antitoxin, PF03937 (Flavinator of succinate dehydrogenase) Sdh5. However, studies have shown that, YgfX interferes with correct cell division and morphology. Furthermore, the function of YgfX-SdhE as a TA system could not be demonstrated in either E. coli or Serratia sp. ATCC 39006. YgfX is predicted to have a short N-terminal cytoplasmic domain followed by two transmembrane helices (TMHs) separated by a short periplasmic loop and finally, a larger C-terminal cytoplasmic domain. The TMHs of YgfX are required for activity, but the sequence of the cytoplasmic 13 N-terminal amino acids is not essential. Furthermore, the amino acids W34 and D117 are not required for localization but are necessary for YgfX multimerization, interaction with SdhE, and YgfX activity. It is proposed that the formation of YgfX multimeric membrane-bound proteins are required to enable the interaction with the cytoplasmic SDH assembly factor SdhE [InterPro reference PUB00083888]. Another study has demonstrated that sdhEygfX (bicistronic operon) affects pig biosynthesis, directly or indirectly, at the level of transcription of the biosynthetic operon (pigA-O) [InterPro reference PUB00066693]. It has also been suggested that, in addition to indirect transcriptional activation of pigA-O, YgfX might facilitate the formation of a terminal pig biosynthetic complex consisting of PigB and PigC [InterPro reference PUB00083888].
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
2 verified sequence examples. FASTA
| UniProt | Protein / organism | Sequence | Provenance |
|---|---|---|---|
| G4V4G3 | Inner membrane protein YgfX Prodigiosinella confusarubida | 143 aa; version 1 UniProt 2026_03 | UNIPROT FETCH1 sibling references |
| Q46824 | Inner membrane protein YgfX Escherichia coli (strain K12) | 135 aa; version 1 UniProt 2026_03 | UNIPROT FETCH1 sibling references |
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
- 1,964
- matches
- 1,965
- proteomes
- 1,959
- taxa
- 2,784
- structures
- 0
- alphafold models
- 1,173
- domain architectures
- 4
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.