1C9H, 3J8E, 4C02, 4IQ2, 4IQC228114226ENSG00000119782ENSMUSG00000020635P68106Q9Z2I2NM_004116NM_054033NM_001322963NM_001322964NM_016863NM_001378816NM_001378817NM_001378818NP_001309892NP_001309893NP_004107NP_473374NP_058559NP_001365745NP_001365746NP_001365747Peptidyl-prolyl cis-trans isomerase FKBP1B is an enzyme that in humans is encoded by the FKBP1B gene.

This encoded protein is a cis-trans prolyl isomerase that binds the immunosuppressants FK506 (tacrolimus) and rapamycin (sirolimus).

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.

[6] Defective interaction between FKB1B and the ryanodine receptor is thought to be a potential mechanism underlying the arrhythmias seen in those with the genetic condition catecholaminergic polymorphic ventricular tachycardia.