All families / PF24729
PF24729: Acb2_Tad1_hairpin
Acb2/Tad1, hairpin domain
- Curation status
- SEEDED
- Seed status
- EX DUF
- Characterization
- UNSCORED
Grounding
PF24729: Acb2/Tad1, hairpin domain
IPR056098: integrated entry for Acb2/Tad1, hairpin domain
Source description
This domain, previously known as DUF7681, is found in phage proteins including Anti-CBASS protein 2 (Acb2) and Thoeris anti-defense 1 (Tad1). It folds into an alpha-helical hairpin that is found either standalone (in Acb2) or in combination with a four-stranded antiparallel beta-sheet domain (in Tad1) [InterPro reference PUB00153173,InterPro reference PUB00156031,InterPro reference PUB00156032]. Prokaryotic anti-phage immune systems use TIR and cGAS-like enzymes to produce 1-3-glycocyclic ADP-ribose; and cyclic dinucleotide and trinucleotide signalling molecules, respectively, which limit phage replication. The Thoeris anti-defence proteins Tad1 and Tad2 are both pronged inhibitors and antagonise immunity alongside Anti-CBASS protein 2. These proteins achieve anti-cyclic-oligonucleotide-based anti-phage signalling system (anti-CBASS) activity by sequestering a considerable amount of cyclic nucleotides. Each of these proteins is using distinct binding pockets. The residues conserved in Tad1 and Acb2 are located near these binding sites [InterPro reference PUB00156032,InterPro reference PUB00156033].
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
3 verified sequence examples. FASTA
| UniProt | Protein / organism | Sequence | Provenance |
|---|---|---|---|
| A0A1C8HPQ3 | Anti-CBASS protein 2 Pseudomonas phage PaMx33 | 93 aa; version 1 UniProt 2026_03 | UNIPROT FETCH1 sibling references |
| P0DW58 | Thoeris anti-defense 1 Clostridium botulinum | 124 aa; version 1 UniProt 2026_03 | UNIPROT FETCH1 sibling references |
| P13314 | Anti-CBASS protein 2 Enterobacteria phage T4 | 88 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
- 831
- matches
- 832
- proteomes
- 784
- taxa
- 1,869
- structures
- 20
- alphafold models
- 333
- domain architectures
- 7
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.