Peptidyl-prolyl cis-trans isomerase FKBP5

FKBP5 (Peptidyl-prolyl cis-trans isomerase FKBP5) is an immunophilin protein with peptidylprolyl isomerase and co-chaperone activities (UniProt: Q13451). It functions as a component of steroid receptor complexes through interaction with heat-shock protein 90 (HSP90) and regulates intracellular trafficking of hormone receptors. FKBP5 also modulates Akt/AKT1 signaling by promoting its dephosphorylation through PHLPP1, and facilitates IKK complex assembly, leading to NF-κB activation and interferon production.

FKBP5 is broadly expressed and participates in cellular stress responses and immune signaling pathways. No disease associations are documented in the UniProt record, though the protein's role in co-chaperone function and kinase regulation suggests relevance to protein homeostasis.

In Alzheimer's Disease, FKBP5 is upregulated in post-mortem AD brain tissue compared to age-matched controls (Chaparral AD proteomics). The mean log2 fold-change is 0.92 across two subcellular fractions in TMT-labeled proteomics analysis of four fractions (P2, P3, S2, S3) from human post-mortem brain tissue, indicating consistent elevation of this co-chaperone protein in the AD brain.