Anti-ATPase inhibitory factor 1 antibodies are protein reagents that detect specific antigens. The ATPase inhibitory factor 1 antigen is another term for the human protein ATP synthase inhibitory factor subunit 1, encoded by the ATP5IF1 gene. The protein is known to function in angiogenesis and erythrocyte differentiation, among other biological roles. Canonically, it has an amino acid length of 106 residues and a mass of 12.2 kilodaltons. Its subcellular localization is in the mitochondria and it is widely expressed in many tissue types. The ATPase inhibitory factor 1 protein is a member of the ATPase inhibitor protein family.