ctpH (G3XDA3, PA2561) review notes

Review session 2026-11-05 (PseudoCAP IBA-seed protocol, tier 2)

Fetched with just fetch-gene PSEAE G3XDA3 --alias ctpH (accession fetch); accession G3XDA3 matches the worklist. Reviewed Swiss-Prot entry. No deep-research provider was used; literature found through the UniProt references and the PubMed MCP, and the cited papers were cached with ai-gene-review fetch-pmid. PMC full text could not be retrieved through the PubMed MCP for the PseudoCAP seed papers with PMC ids (empty body), so those were read as abstracts; the confidence rule is not engaged because no defect is recorded.

Identity

MCP with two TM helices (40-60, 217-237) around a periplasmic ligand binding domain, cytoplasmic HAMP and MCPsignal domains (PF00672, PF00015; PTHR32089:SF120). Constitutively expressed; not in the Pho regulon, unlike CtpL.

Literature

Seed paper PMID:10852870; PMID:10852870 (abstract only; PMC body not returned).
Direct binding, full text read PMID:27353565; PMID:27353565.

Annotation decisions

GO:0004888 IEA: ACCEPT, core MF. Chemotaxis (IBA, IEA, IMP): ACCEPT. Detection of phosphate ion IMP: ACCEPT (the receptor binds Pi itself).
Plasma membrane ACCEPT; membrane TOO_GENERAL; signal transduction MODIFY to GO:0007166.
NEW GO:0042301 phosphate ion binding (IDA, PMID:27353565).
Action counts: ACCEPT 6, MODIFY 1, TOO_GENERAL 1, NEW 1.

PseudoCAP IBA-seed assessment

Node-level assessment: see genes/PSEAE/pctB/pctB-notes.md (recorded once there); summary repeated below.

PTN node	node term	n_seeds	leaf IBAs	seed annotation (term, evidence, PMID)	verdict	rationale	other seeds	IBD stands without this seed?
PTN001280296	GO:0006935 chemotaxis	10	215 (22 taxa)	GO:0006935, IMP, PMID:10852870	SOUND	Abstract states the ctpH mutant loses Pi taxis at high Pi and the ctpH ctpL double mutant at all Pi levels; CtpH-LBD binds Pi directly (PMID:27353565).	PctA, PctB/PctC, CtpH, CtpL, CtpM, Aer (PseudoCAP IMP); B. subtilis McpC (IDA/IMP positive chemotaxis); B. subtilis and H. salinarum HemAT (IDA aerotaxis)	Yes; independent IDA seeds (McpC, two HemATs) and six other PseudoCAP seeds

No source_defects were recorded; no GO_CENTRAL defect for the shared node.