VAPA is an endoplasmic reticulum membrane-anchored adaptor of the VAMP-associated protein family. Its cytoplasmic major sperm protein (MSP) domain recognizes FFAT motifs in partner proteins, linking the endoplasmic reticulum to other membranes and supporting lipid-transfer contact sites. The horse protein retains the MSP domain, coiled-coil region and C-terminal membrane anchor characteristic of mammalian VAPA.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0005789 endoplasmic reticulum membrane | IEA GO_REF:0000120 | ACCEPT | Summary: The conserved C-terminal membrane anchor and mammalian VAPA experiments support ER membrane residence. Reason: The selected horse protein retains the MSP domain and terminal transmembrane helix and is 98.4% identical across all 249 human canonical residues. This architecture supports transfer of the experimentally established ER-anchored adaptor role. The extra horse segment lies in the linker and corresponds to an alternatively spliced human region; it does not replace the membrane anchor. ARBA localization text is not used as validation. Supporting Evidence: PMID:33124732 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. |
| GO:0005886 plasma membrane | IEA GO_REF:0000044 | KEEP AS NON CORE | Summary: The peripheral plasma-membrane/tight-junction pool is supported by mammalian localization evidence. Reason: Human VAP-33 antibodies colocalize with occludin at tight junctions, and human VAPA can be recruited to plasma-membrane contact sites. Conservation supports this as a plausible horse localization, while the principal role is ER membrane anchoring. This is a mammalian transfer rather than a horse imaging experiment. Supporting Evidence: PMID:10523508 Antibodies to the human VAP-33 co-localized with occludin at the tight junction in many tissues and tissue culture cell lines. |
| GO:0005923 bicellular tight junction | IEA GO_REF:0000044 | KEEP AS NON CORE | Summary: The peripheral plasma-membrane/tight-junction pool is supported by mammalian localization evidence. Reason: Human VAP-33 antibodies colocalize with occludin at tight junctions, and human VAPA can be recruited to plasma-membrane contact sites. Conservation supports this as a plausible horse localization, while the principal role is ER membrane anchoring. This is a mammalian transfer rather than a horse imaging experiment. Supporting Evidence: PMID:10523508 Antibodies to the human VAP-33 co-localized with occludin at the tight junction in many tissues and tissue culture cell lines. |
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