Anti-IF antibodies are protein reagents that detect specific antigens. The IF antigen is another term for the human protein cobalamin binding intrinsic factor, encoded by the CBLIF gene. The protein is reported to promote absorption of the essential vitamin cobalamin (Cbl) in the ileum. Canonically, it has an amino acid length of 417 residues and a mass of 45.4 kilodaltons. It is a secreted protein and it is expressed in the stomach and testis. The IF protein is a member of the Eukaryotic cobalamin transport proteins protein family.