Anti-VPS39 subunit of HOPS complex antibodies are used for the immunodetection of the protein encoded by the VPS39 gene. In humans, the canonical protein has a reported length of 886 amino acid residues and a mass of 101.8 kDa. Its subcellular localization is in the membrane, lysosomes and cytoplasm. Alternative splicing is reported to yield 2 different isoforms for this protein. It is found to be widely expressed, with highest levels in the heart, skeletal muscle, kidney, pancreas, brain, placenta and spleen. A member of the VAM6/VPS39 protein family, it is a reported regulator of TGF-beta/activin signaling, inhibiting SMAD3- and activating SMAD2-dependent transcription. Other names for this target antigen include VAM6, hVam6p, vam6/Vps39-like protein, TRAP1-like protein, VPS39, HOPS complex subunit, and TLP. Gene orthologs have been identified in the mouse, rat, bovine, frog, zebrafish, chimpanzee and chicken species.