A number of ELISA Kits are available that target OTK4, an alias of the protein, FK506 binding protein 1B. The human protein, encoded by the gene FKBP1B, is an enzyme and a member of the FKBP-type PPIase family, FKBP1 subfamily. It is also present in other species, such as: Mouse, Rat, Zebrafish, Frog, Chicken. Other name designations may also include: OTK4; FKBP12.6; PPIase; FKBP9; calstabin 2. OTK4 has a reported size of 11.8 kilodaltons with an amino acid length of 108. There are 2 recognized isoforms.