The blood vessel diameter maintenance annotation derives from the Vasoactive keyword, which does not encode the direction of the effect.

The cGMP biosynthetic process and receptor guanylyl cyclase signaling pathway annotations were propagated from the PANTHER natriuretic peptide tree. Notably, the PANTHER subfamily assigned is PTHR12167:SF2 "C-TYPE NATRIURETIC PEPTIDE", which contradicts the ARBA-derived protein name in the same record.

Hormone activity and extracellular region come from combined automated methods applied to the Hormone and Secreted keywords.

The natriuretic peptide abundantly transcribed in the D. rotundus principal submaxillary gland is C-type natriuretic peptide, and bat and human CNP share a similar primary sequence and domain structure. This is the study whose EMBL submission (JAA44981.1, salivary gland) underlies the K9IWC0 accession.

The authors assign vasodilation as the function of the bat salivary CNP, placing it alongside PACAP among the vasodilators that support blood flow during feeding.

CNP signals through NPR-B (NPR2, guanylate cyclase B) and the clearance receptor NPR-C (NPR3), not through NPR1. This is the receptor distinction that the misassigned NPPB name obscures.

Unlike ANP and BNP, CNP acts locally as a paracrine or autoregulator and is cleared rapidly from the circulation, being present in plasma at very low concentrations; it is a potent relaxant of arterial and venous smooth muscle.

The natriuretic peptide receptors carry a C-terminal guanylate cyclase domain that generates cGMP as the second messenger for vasodilation.

Global pairwise alignment against the three human natriuretic peptide precursors gives 72.3% identity to NPPC/CNP versus 31.9% to each of NPPB/BNP and NPPA/ANP, identifying K9IWC0 unambiguously as a C-type natriuretic peptide.

The K9IWC0 precursor terminates exactly at the second ring cysteine with no trailing residues, which matches NPPC and excludes NPPA (5 trailing residues) and NPPB (6).

The analysis is sequence-based orthology assignment only; no D. rotundus natriuretic peptide has been purified or assayed and receptor usage is inferred from mammalian CNP biology.

The ARBA-derived protein name is "Natriuretic peptides B" with BNP alternative names, but the PANTHER subfamily in the same record is PTHR12167:SF2 "C-TYPE NATRIURETIC PEPTIDE". The record is internally inconsistent about which paralogue this is.

The FUNCTION block describes cardiac hormone biology acting through NPR1 to produce cGMP. This text belongs to BNP/ANP; CNP signals through NPR2. It should not be used to justify NPR1-specific annotations for this protein.

The precursor has a signal peptide (1-23) and is annotated as Secreted, belonging to the natriuretic peptide family.

The report accepted the UniProt "Natriuretic peptides B" name without checking it and built its entire narrative on BNP cardiac-biomarker biology (NT-proBNP thresholds, heart failure diagnostics, NPR1 agonist antibodies), none of which applies to a salivary C-type natriuretic peptide.

The report does correctly state the receptor division of labour within the family, which is what makes the paralogue misassignment consequential.