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

[6] As an Hsp90-associated co-chaperone that regulates the responsiveness of steroid hormone receptors, FKBP51 plays an important role in stress endocrinology and glucocorticoid signaling.

[6] The FKBP5 gene has been found to have multiple polyadenylation sites[5] and is statistically associated with a higher rate of depressive disorders.

[7] Decreased methylation in the promoter of the FKBP5 gene has been observed in blood samples from patients with neurodegenerative diseases.

[8] As a key player in several diseases like stress-related disorders, chronic pain, and obesity, FKBP51 is an attractive drug target.