Anti-ERVK-9 antibodies are used in the immunodetection of the protein endogenous retrovirus group K member 9. In humans, the canonical protein has a reported length of 1117 amino acid residues and a mass of 123.6 kDa. Its subcellular localization is in the cell membrane. A member of the Beta type-B retroviral polymerase protein family, ERVK-9 is known to be involved with proteolysis. Post-translational modifications have been described, including protein cleavage and myristoylation.