id: A0A2G9RZF1 gene_symbol: A0A2G9RZF1 product_type: PROTEIN status: DRAFT taxon: id: NCBITaxon:8400 label: Aquarana catesbeiana description: >- A0A2G9RZF1 is a gene prediction fragment from the fragmented draft genome assembly of Aquarana catesbeiana (American bullfrog). The 156-amino acid ORF (AB205_0007200) encodes a single CUB domain (residues 31-147), but scaffold KV928989 contains two additional consecutive ORFs (A0A2G9RZH1 with EGF+CUB domains, and A0A2G9RZI6 with CUB+EGF+CUB domains, the latter explicitly flagged as a fragment by UniProt) whose combined domain architecture (CUB-EGF-CUB-CUB-EGF-CUB) matches the C-terminal region of a tolloid-family metalloprotease (BMP-1 or TLL1). A 2024 chromosome-level assembly (GCF_042186555.1) with ~17,000-fold better contiguity encodes complete BMP-1 (XP_073478370.1, 1,020 aa, LG03) and TLL1 (XP_073462190.1, 1,005 aa, LG01), confirming the original draft produced fragmented gene models. The complete gene product is a tolloid-family metalloprotease with metalloendopeptidase activity. No experimental data exist for this protein (UniProt protein evidence level 4: Predicted). references: - id: PMID:29127278 title: "The North American bullfrog draft genome provides insight into hormonal regulation of long noncoding RNA" reference_review: relevance: LOW correctness: VERIFIED review_notes: >- This is the bullfrog genome paper cited by UniProt for the nucleotide sequence. It provides the genomic context but no functional characterization of this specific gene. - id: file:AQUCT/A0A2G9RZF1/A0A2G9RZF1-deep-research-falcon.md title: "Deep research report for A0A2G9RZF1" publication_type: DEEP_RESEARCH reference_review: relevance: MEDIUM correctness: UNVERIFIED review_notes: >- The falcon deep research correctly identifies the protein as a CUB domain-containing protein and provides a thorough domain-based functional inference from recent literature on CUB domain proteins. No direct literature exists for this specific protein, so all functional inferences are based on domain architecture and family membership comparisons. - id: file:AQUCT/A0A2G9RZF1/A0A2G9RZF1-hypotheses/core-function-1-go-0005201/openscientist.md title: "OpenScientist deep research: GO:0005201 as core function of A0A2G9RZF1" publication_type: DEEP_RESEARCH reference_review: relevance: HIGH correctness: VERIFIED review_notes: >- OpenScientist autonomous investigation refuted GO:0005201 assignment on three independent grounds: (1) semantic mismatch -- GO:0005201 describes structural ECM proteins, not CUB-domain interaction modules; (2) PCPE-1 FunFam evidence chain failure -- PCPE-1 real function is peptidase activator activity (GO:0016504), and single CUB domains cannot perform PCPE-1 function (requires cooperative CUB1+CUB2 per PMID:19801683); (3) A0A2G9RZF1 is a gene prediction fragment from a poorly assembled genome -- a 2024 chromosome-level assembly (GCF_042186555.1) encodes complete BMP-1 (1,020 aa) and TLL1 (1,005 aa). - id: PMID:21954942 title: "Structure and properties of the Ca(2+)-binding CUB domain, a widespread ligand-recognition unit involved in major biological functions" reference_review: relevance: HIGH correctness: VERIFIED review_notes: >- Authoritative review of CUB domain biology. Establishes CUB domains as protein-protein interaction modules with beta-sandwich fold, not structural ECM components. Cited by OpenScientist report. - id: PMID:19801683 title: "Strong cooperativity and loose geometry between CUB domains are the basis for procollagen C-proteinase enhancer activity" reference_review: relevance: HIGH correctness: VERIFIED review_notes: >- Key experimental paper demonstrating that individual CUB domains lose >1,000-fold binding affinity compared to the CUB1+CUB2 pair. Refutes functional transfer from PCPE-1 to single-CUB-domain proteins. existing_annotations: [] core_functions: - description: >- A0A2G9RZF1 is almost certainly a gene prediction fragment from a poorly assembled draft genome, representing one CUB domain from a much larger (~1,000 aa) tolloid-family metalloprotease (BMP-1 or TLL1). The 156-amino acid ORF cannot be meaningfully annotated with a specific molecular function. GO:0005201 (extracellular matrix structural constituent) was previously hypothesized based on CATH FunFam classification to PCPE-1, but this was refuted by OpenScientist analysis on three grounds: (1) GO:0005201 describes structural ECM proteins (collagens, elastin), not CUB-domain interaction modules; (2) PCPE-1 real function is peptidase activator activity (GO:0016504, IDA), and individual CUB domains cannot perform PCPE-1 function (requires cooperative CUB1+CUB2 with >1,000-fold higher affinity than single domains); (3) genomic context shows three consecutive fragmented ORFs on scaffold KV928989 matching tolloid-like architecture, and a 2024 chromosome-level assembly (GCF_042186555.1) encodes complete BMP-1 (1,020 aa) and TLL1 (1,005 aa). The conservative MF assignment of protein binding reflects only that CUB domains are established protein-protein interaction modules; the actual function of the complete gene product would be metalloendopeptidase activity. molecular_function: id: GO:0003674 label: molecular_function locations: - id: GO:0005576 label: extracellular region knowledge_gaps: - gap_statement: >- A0A2G9RZF1 is a gene prediction fragment, not a complete protein. Its true molecular function cannot be determined from this 156-aa fragment. The complete gene product is a tolloid-family metalloprotease (BMP-1 or TLL1) with metalloendopeptidase activity, but which specific gene (BMP-1 on LG03 or TLL1 on LG01 of the chromosome-level assembly) corresponds to this fragment has not been determined by sequence alignment. boundary: >- The fragment contains a single CUB domain (residues 31-147) that mediates protein-protein interactions in the extracellular space. Scaffold KV928989 encodes three consecutive ORFs whose combined domains match the C-terminal region of a tolloid-family metalloprotease. A 2024 chromosome-level assembly (GCF_042186555.1) confirms complete BMP-1 (1,020 aa) and TLL1 (1,005 aa) exist in this species. gap_kind: - BIOLOGY significance: >- The fragment status means no GO molecular function annotation should be confidently applied to this entry. When the UniProt proteome (UP000228934) is updated from the 2017 draft to the 2024 chromosome-level assembly, this entry should be superseded by a complete gene model. supported_by: - reference_id: file:AQUCT/A0A2G9RZF1/A0A2G9RZF1-hypotheses/core-function-1-go-0005201/openscientist.md supporting_text: >- [OpenScientist verdict: REFUTED. GO:0005201 is semantically inappropriate for CUB-domain proteins, the PCPE-1 FunFam evidence chain fails (PCPE-1 function is peptidase activator activity, individual CUB domains lose >1,000-fold affinity), and A0A2G9RZF1 is a gene prediction fragment from a fragmented genome assembly confirmed by a 2024 chromosome-level assembly encoding complete BMP-1 (1,020 aa) and TLL1 (1,005 aa)] - reference_id: PMID:19801683 supporting_text: >- only those containing both CUB1 and CUB2 were capable of enhancing BMP-1 activity and binding to a mini-procollagen substrate with nanomolar affinity. Both these properties were lost by individual CUB domains, which had dissociation constants at least three orders of magnitude higher - reference_id: PMID:21954942 supporting_text: >- CUB domains are 110-residue protein motifs exhibiting a β-sandwich fold and mediating protein-protein interactions in various extracellular proteins - reference_id: file:AQUCT/A0A2G9RZF1/A0A2G9RZF1-uniprot.txt supporting_text: >- [UniProt record: CUB domain at residues 31-147; InterPro IPR000859 CUB_dom; Pfam PF00431 CUB; PANTHER PTHR24251 OVOCHYMASE-RELATED; protein existence level 4 (Predicted)] suggested_questions: - question: >- Which complete tolloid-family gene does this fragment correspond to -- BMP-1 (XP_073478370.1 on LG03) or TLL1 (XP_073462190.1 on LG01)? A BLAST alignment of scaffold KV928989 against the chromosome-level assembly (GCF_042186555.1) would definitively resolve this. OpenScientist analysis confirmed A0A2G9RZF1 is a gene prediction fragment, but the specific gene identity remains undetermined. - question: >- When will the UniProt proteome for Aquarana catesbeiana (UP000228934) be updated from the 2017 draft assembly to the 2024 chromosome-level assembly (GCF_042186555.1)? This update would supersede the fragment entries (A0A2G9RZF1, A0A2G9RZH1, A0A2G9RZI6) with complete gene models carrying appropriate metalloendopeptidase annotations. - question: >- Does Aquarana catesbeiana have a genuine PCPE-1/PCOLCE1 ortholog separate from the tolloid-family metalloproteases? A reciprocal best BLAST of human PCPE-1 (Q15113) against the chromosome-level proteome would clarify whether the CATH FunFam classification to PCPE-1 reflects any real orthology relationship or is purely fold-level similarity. suggested_experiments: - hypothesis: >- A0A2G9RZF1 is a fragment of a BMP-1 or TLL1 tolloid-family metalloprotease, not a standalone protein. description: >- Align scaffold KV928989 from the RCv2.1 draft assembly against the chromosome-level assembly (GCF_042186555.1) using BLAST or minimap2 to definitively map A0A2G9RZF1 to either BMP-1 (XP_073478370.1, LG03) or TLL1 (XP_073462190.1, LG01). This computational experiment would resolve the remaining ambiguity about gene identity. experiment_type: bioinformatics - hypothesis: >- The complete tolloid-family metalloprotease corresponding to A0A2G9RZF1 has metalloendopeptidase activity and functions in procollagen processing or BMP signaling regulation. description: >- Clone the full-length BMP-1 or TLL1 gene from Aquarana catesbeiana cDNA using the chromosome-level assembly as reference, express recombinantly, and assay metalloendopeptidase activity against procollagen or Chordin substrates. Compare with Xenopus Xolloid, the closest well-characterized amphibian ortholog. experiment_type: biochemistry