CG42404 (Q9VFA8): evidence and ProtNLM claim review

CG42404 is a 1133-residue VWFC-domain protein with a predicted membrane-spanning segment near its N terminus. Its extracellular-domain-like architecture and membrane association are compatible with a cell-surface interaction protein, but ligand specificity, topology, and biological activity are unresolved.

Exact input: Q9VFA8, 1133 residues. The accession was fetched explicitly with the gene-directory alias; no canonical-sequence substitution is made.

Raw emitted predictions: CG42404-predictions-source.json. Source features: CG42404-uniprot.txt, with an exact extraction in CG42404-sequence-evidence.json.

Sequence and domain evidence

These are sequence/domain observations or explicitly named feature predictions, not measurements of biological function. ARBA assertions and ProtNLM-derived UniProt names are not counted as validation.

DR   InterPro; IPR042378; IDD.
DR   InterPro; IPR001007; VWF_dom.
FT   TRANSMEM        103..125
FT                   /note="Helical"
FT                   /evidence="ECO:0000256|SAM:Phobius"
FT   DOMAIN          27..92
FT                   /note="VWFC"
FT                   /evidence="ECO:0000259|PROSITE:PS50184"

ProtNLM claims

The snapshot emits names and location/keyword statements, with no GO or EC prediction for this target. Each actual statement is assessed below; no GO term has been substituted for it. Categories follow the function-prediction rubric, with nonspecific “uncharacterized” names marked UNC because they contain no testable function. CNN records an independently supported existing annotation; it does not assert a particular training-set composition.

Kind	Verbatim emitted statement	Assessment	Evidence and limitation
Name	VWFC domain-containing protein	CNN	The VWFC domain at residues 27-92 is supported independently by PROSITE PS50184 and InterPro IPR001007. This validates the domain name without specifying a von Willebrand factor function.
Location	Membrane (SL-0162)	CNN	The Phobius transmembrane segment at residues 103-125 supports the broad membrane location already represented by curated IBA. It does not establish secretion as a soluble protein.
Keyword	Signal (KW-0732)	UNC	The source record contains an internal transmembrane segment but no cleavable signal-peptide feature. A signal anchor can route a membrane protein without a cleaved N-terminal signal peptide; the emitted Signal keyword requires a resolved N terminus and topology.

Literature evidence

No target-specific primary finding is used to establish a molecular activity here. The current assessment is bounded by exact-record architecture and the explicitly identified curated inferences.

Annotation decisions

GO:0003674 molecular_function (ND): ACCEPT. A VWFC domain does not specify a ligand or a receptor activity for this fly product.
GO:0005575 cellular_component (ND): MODIFY. The exact record carries a Phobius transmembrane segment at residues 103-125 and a curated IBA membrane annotation. The broad membrane term is supported without identifying a particular organelle.
GO:0008150 biological_process (ND): ACCEPT. Domain and topology evidence do not establish a developmental or signaling pathway.
GO:0016020 membrane (IBA): ACCEPT. A predicted membrane-spanning segment at residues 103-125 is consistent with the existing phylogenetically curated membrane annotation; specific topology and tissue function are unresolved.

Research provenance

Genuine external literature research is requested through the repository Falcon wrapper, with perplexity-lite configured as fallback. Provider output is retained separately as CG42404-deep-research-<provider>.md; its source leads are checked against the underlying publications and exact sequence record.