hbt (Q9VK03): evidence and ProtNLM claim review

Headbutt is a 451-residue Rost-family protein with six predicted transmembrane helices. It is an integral membrane protein with an unresolved molecular activity and biological role for this isoform.

Exact input: Q9VK03, 451 residues. The accession was fetched explicitly with the gene-directory alias; no canonical-sequence substitution is made.

Raw emitted predictions: hbt-predictions-source.json. Source features: hbt-uniprot.txt, with an exact extraction in hbt-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; IPR049352; Rost.
FT   TRANSMEM        40..63
FT                   /note="Helical"
FT                   /evidence="ECO:0000256|SAM:Phobius"
FT   TRANSMEM        75..98
FT                   /note="Helical"
FT                   /evidence="ECO:0000256|SAM:Phobius"
FT   TRANSMEM        123..145
FT                   /note="Helical"
FT                   /evidence="ECO:0000256|SAM:Phobius"
FT   TRANSMEM        157..177
FT                   /note="Helical"
FT                   /evidence="ECO:0000256|SAM:Phobius"
FT   TRANSMEM        184..205
FT                   /note="Helical"
FT                   /evidence="ECO:0000256|SAM:Phobius"
FT   TRANSMEM        228..250
FT                   /note="Helical"
FT                   /evidence="ECO:0000256|SAM:Phobius"

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	Uncharacterized protein	UNC	The nonspecific name is consistent with unresolved molecular activity but is not a testable prediction. Rost-family membership does not itself establish a transported substrate.
Location	Membrane (SL-0162)	CNN	Six predicted membrane-spanning helices strongly support the broad membrane claim already present as a curated ISS annotation. This does not specify a membrane or transport mechanism.

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. Six membrane-spanning segments and a Rost-family domain do not establish a transporter substrate or catalytic activity.
GO:0008150 biological_process (ND): ACCEPT. The exact Headbutt isoform lacks a sufficiently grounded physiological function in the retrieved evidence.
GO:0016020 membrane (ISS): ACCEPT. The six Phobius transmembrane segments between residues 40 and 250 independently support the existing ISS membrane annotation. The membrane identity and transport activity 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 hbt-deep-research-<provider>.md; its source leads are checked against the underlying publications and exact sequence record.