Anti-VMA21 vacuolar H+-ATPase homolog antibodies are used in antigen-specific immunodetection in biological samples. The target VMA21 vacuolar H+-ATPase homolog is a known alias name of the protein vacuolar ATPase assembly factor VMA21, encoded by the VMA21 gene in humans. This 101-amino acid residue protein is known to be required for the assembly of the V0 complex of the vacuolar ATPase (V-ATPase) in the endoplasmic reticulum. It is localized to the cytoplasmic vesicles and ER of the cell. Other synonyms for VMA21 vacuolar H+-ATPase homolog include vacuolar ATPase assembly integral membrane protein VMA21 and VMA21 vacuolar H+-ATPase homolog.