Anti-FKBP prolyl isomerase 5 antibodies are used for the immunodetection of the protein encoded by the FKBP5 gene. In humans, the canonical protein has a reported length of 457 amino acid residues and a mass of 51.2 kDa. Its subcellular localization is in the nucleus and cytoplasm. Alternative splicing is reported to yield 2 different isoforms for this protein. It is reported to be widely expressed, enriched in testis compared to other tissues. It is noted to be involved in protein folding. Post-translational modifications have been described, including acetylation. Other names for this target antigen include AIG6 and FKBP51. Gene orthologs have been identified in the mouse, rat, bovine, zebrafish, chimpanzee and chicken species.