FKBP1B
（重定向自FKBP12.6）
Peptidyl-prolyl cis-trans isomerase FKBP1B is an enzyme that in humans is encoded by the FKBP1B gene.
The protein encoded by this gene is a member of the immunophilin protein family, which play a role in immunoregulation and basic cellular processes involving protein folding and trafficking. This encoded protein is a cis-trans prolyl isomerase that binds the immunosuppressants FK506 (tacrolimus) and rapamycin (sirolimus). It is highly similar to the FK506-binding protein 1A. Its physiological role is thought to be in excitation-contraction coupling in cardiac muscle. There are two alternatively spliced transcript variants of this gene encoding different isoforms.