The selected 294-aa horse sequence aligns to all 249 human VAPA canonical residues at 98.4% identity. The insertion follows residue 139 and corresponds to the alternatively spliced human region documented in Q9P0L0; the MSP domain and terminal membrane anchor are intact. This supports transfer of the mammalian adaptor mechanism without equating MSP-domain membership with sperm motility.
PMID:33124732(https://pubmed.ncbi.nlm.nih.gov/33124732/) supplies direct structural and biochemical FFAT-binding/contact-site evidence; “VAP‐A, VAP‐B, and MOSPD2 are anchored in the ER membrane by a carboxyl‐terminal transmembrane domain with their MSP domain projecting into the cytosol.” PMID:10523508(https://pubmed.ncbi.nlm.nih.gov/10523508/) supplies the peripheral tight-junction localization: “Antibodies to the human VAP-33 co-localized with occludin at the tight junction in many tissues and tissue culture cell lines.” The latter quote has line breaks in the cached abstract. Horse ARBA descriptions repeat these conclusions but do not validate them independently.
Horse UniProt is unreviewed and cites genome sequencing/identification, not a dedicated horse functional study; no horse-specific Edison job was selected. A completed human Falcon report has been inspected.