FKBP3

FKBP3, commonly referred to as FKBP25, is a member of the FKBP family of peptidyl-prolyl cis-trans isomerases (immunophilins). It is encoded by the FKBP3 gene in humans. The protein features an N-terminal basic region that promotes DNA and histone binding and a C-terminal PPIase domain. Compared with some cytosolic FKBPs, FKBP25 is predominantly localized to the nucleus and associates with chromatin.

Functionally, FKBP25 participates in transcriptional regulation and chromatin remodeling and is implicated in the DNA damage response. Through its interactions with chromatin-associated proteins and transcription factors, it is thought to influence gene expression programs. It has been reported to interact with components of NF-κB signaling and with histone-modifying complexes, linking it to inflammatory and stress responses.

Immunophilin and drug-binding properties: As a member of the immunophilin family, FKBP25 can bind immunosuppressant ligands such as FK506 and rapamycin in vitro, though the physiological relevance of such binding for FKBP25 remains to be fully clarified.

Clinical and research context: Altered FKBP3 expression or function has been observed in various cancers and in immune-related contexts, making it a subject of ongoing investigation for its roles in chromatin regulation and DNA repair. Overall, FKBP3/FKBP25 is recognized as a nuclear immunophilin with chromatin-associated functions rather than a classical cytosolic PPIase.