FKBP12: an immunophilin and peptidyl-prolyl cis-trans isomerase that binds to the immunosuppressant drugs FK506 (a.k.a. tacrolimus or Fujimycin) and rapamycin (a.k.a. Sirolimus). The FKBP12/rapamycin complex binds NFAT transcription factors and inhibits the induction of T cell genes including IL-2, IL-3, IL-4, TNF-alpha and GM-CSF. FK506 is used in treating patients after organ transplant and those suffering from autoimmune disorders. The immunosuppressant activity of FKBP12 is not apparently related to its prolyl isomerase activity. The FKBP12/rapamycin complex inhibits the mammalian target of rapamycin (mTOR) pathway by directly binding the mTOR Complex1 (mTORC1). mTORC1 contains Raptor, mLST8, and PRAS40, and interacts with DEPTOR, which inhibits its activity. mTOR, a S/T protein kinase, is a central regulator of cellular growth and metabolism. Its inhibition enhances the dependence on aerobic glycolysis in leukemic cells.
Protein type: EC 5.2.1.8; Isomerase
Chromosomal Location of Human Ortholog: 20p13
Cellular Component: endoplasmic reticulum membrane; sarcoplasmic reticulum membrane; membrane; cytoplasm; nerve terminal; Z disc; cytosol
Molecular Function: signal transducer activity; protein binding; FK506 binding; enzyme binding; protein homodimerization activity; peptidyl-prolyl cis-trans isomerase activity; activin binding; macrolide binding; calcium channel inhibitor activity; Hsp70 protein binding; SMAD binding; transforming growth factor beta receptor binding
Biological Process: heart morphogenesis; protein maturation via protein folding; protein peptidyl-prolyl isomerization; protein folding; positive regulation of protein binding; T cell activation; response to caffeine; T cell proliferation; regulation of protein localization; negative regulation of protein amino acid phosphorylation; muscle contraction; transforming growth factor beta receptor signaling pathway; negative regulation of release of sequestered calcium ion into cytosol; fibril organization and biogenesis; ventricular cardiac muscle morphogenesis; protein refolding; response to iron ion; regulation of immune response; positive regulation of I-kappaB kinase/NF-kappaB cascade; cytokine and chemokine mediated signaling pathway; regulation of activin receptor signaling pathway; SMAD protein complex assembly; negative regulation of protein phosphatase type 2B activity; 'de novo' protein folding; positive regulation of protein ubiquitination; release of sequestered calcium ion into cytosol
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