Peptidyl-prolyl cis-trans isomerase FKBP1B

Peptidyl-prolyl cis-trans isomerase FKBP1B (FKBP1B) is a 108-amino acid protein that catalyzes cis-trans isomerization of proline imidic peptide bonds in oligopeptides, accelerating protein folding (UniProt: P68106). The protein also has potential involvement in immunosuppressive and toxic effects of FK506 and rapamycin through its peptidyl-prolyl isomerase activity.

FKBP1B is expressed in human tissues and participates in protein quality control pathways. No specific tissue localization or pathway associations are detailed in the UniProt record (UniProt: P68106), and no developmental or degenerative disease annotations are curated in the source database.

In Alzheimer's disease, FKBP1B shows reduced abundance in post-mortem AD brain compared to age-matched controls, with a mean log2 fold-change of −0.74 (Chaparral AD proteomics). This downregulation was observed in human post-mortem AD brain tissue analyzed by TMT-labeled quantitative proteomics across subcellular fractions, suggesting diminished protein folding capacity or altered chaperone dynamics may contribute to AD pathology.