All families / PF01985
PF01985: CRS1_YhbY
CRS1 / YhbY (CRM) domain
- Curation status
- SEEDED
- Seed status
- EX DUF
- Characterization
- UNSCORED
Grounding
PF01985: CRS1 / YhbY (CRM) domain
IPR001890: integrated entry for CRS1 / YhbY (CRM) domain
Source description
Escherichia coli YhbY is associated with pre-50S ribosomal subunits, which implies a function in ribosome assembly. GFP fused to a single-domain CRM protein from maize localises to the nucleolus, suggesting that an analogous activity may have been retained in plants [InterPro reference PUB00043747]. A CRM domain containing protein in plant chloroplasts has been shown to function in group I and II intron splicing [InterPro reference PUB00044700]. In vitro experiments with an isolated maize CRM domain have shown it to have RNA binding activity. These and other results suggest that the CRM domain evolved in the context of ribosome function prior to the divergence of Archaea and Bacteria, that this function has been maintained in extant prokaryotes, and that the domain was recruited to serve as an RNA binding module during the evolution of plant genomes [InterPro reference PUB00043747]. YhbY has a fold similar to that of the C-terminal domain of translation initiation factor 3 (IF3C), which binds to 16S rRNA in the 30S ribosome [InterPro reference PUB00019352][InterPro reference PUB00019353].
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
9 verified sequence examples. FASTA
| UniProt | Protein / organism | Sequence | Provenance |
|---|---|---|---|
| F4J2U9 | CRM-domain containing factor CFM3A, chloroplastic/mitochondrial Arabidopsis thaliana | 881 aa; version 1 UniProt 2026_03 | PTM REGISTRY MIRROR |
| F4JVH1 | CRM-domain containing factor CFM3B, chloroplastic Arabidopsis thaliana | 907 aa; version 1 UniProt 2026_03 | UNIPROT FETCH |
| P0AGK4 | RNA-binding protein YhbY Escherichia coli (strain K12) | 97 aa; version 1 UniProt 2026_03 | PTM REGISTRY MIRROR |
| P54454 | Probable RNA-binding protein YqeI Bacillus subtilis (strain 168) | 96 aa; version 1 UniProt 2026_03 | UNIPROT FETCH |
| Q58068 | Probable RNA-binding protein MJ0652 Methanocaldococcus jannaschii (strain ATCC 43067 / DSM 2661 / JAL-1 / JCM 10045 / NBRC 100440) | 134 aa; version 1 UniProt 2026_03 | UNIPROT FETCH |
| Q8L7C2 | CRM-domain containing factor CFM2, chloroplastic Arabidopsis thaliana | 1011 aa; version 1 UniProt 2026_03 | UNIPROT FETCH |
| Q8VYD9 | CRS2-associated factor 1, mitochondrial Arabidopsis thaliana | 405 aa; version 1 UniProt 2026_03 | PTM REGISTRY MIRROR |
| Q9LF10 | Chloroplastic group IIA intron splicing facilitator CRS1, chloroplastic Arabidopsis thaliana | 720 aa; version 2 UniProt 2026_03 | UNIPROT FETCH |
| Q9LT57 | CRM-domain containing factor CFM9, mitochondrial Arabidopsis thaliana | 491 aa; version 1 UniProt 2026_03 | PTM REGISTRY MIRROR |
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
- 15,752
- matches
- 23,182
- proteomes
- 8,486
- taxa
- 12,703
- structures
- 6
- alphafold models
- 11,674
- domain architectures
- 130
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.