FK506 Binding Protein 1A, Recombinant, Human (FKBP1A, FK506 Binding Protein 12kD, FKBP12)

FK506 binding protein, 12 kilodalton molecular weight (FKBP12), also called FKBP1, was originally characterized as a peptidyl-prolyl isomerase that catalyzes the transition between cis- and trans-proline residues critical for proper folding of proteins. The macrolide immunosuppressants FK506 (Tacrolimus) and rapamycin bind to FKBP12 with high affinity, while the structurally related-compound cyclosporine binds with a much lower affinity (1). The binding of these drugs causes FKBP12 to become a potent inhibitor of calcineurin phosphatase activity 2 and TOR kinase activity (3). The inhibition of protein phosphatase activity is highly selective for calcineurin (2), making the FK506/FKBP12 complex a useful tool in the study of this enzyme. Knockout mice lacking FKBP12 are morphologically normal, but develop cardiomyopathies that may be related to dysregulation of ryanodyne receptors (4).\n\nSource: \nE. coli-expressed recombinant protein.\n\nMolecular Mass: \nAmino acid residues 2-108 of human FKBP12 (Accession # BC005147) with a C-terminal His6 sequence was expressed in E. coli. FKBP12 purified from the soluble fraction of disrupted E. coli has a predicted molecular weight of 12,775 daltons.\n\nActivity: \nMeasured by its ability to inhibit calcineurin phosphatase activity in the presence of FK506. The IC50 for inhibition of calcineurin activity is 28 nM. Proline isomerase activity was demonstrated but not used for quality control.\n\nHandling: \nCentrifuge the vial before opening to recover entire contents of the vial. Due to possible sublimation during storage, the buffer volume may decrease over time. The product is sold by mass and the amount of protein will remain constant. To ensure quantitative recovery, we suggest the stock solution be made in the original vial.\n\nStorage: \nStore frozen at -20 degrees C in a manual defrost freezer. Avoid repeated freeze-thaw cycles.

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SPECIFICATIONS

Catalog Number

F4150-11A

Size

100ug

Form

Supplied as a liquid in 20mM HEPES, 0.1M NaCl, pH 7.5.

Purity

(same/more than) 95%, as determined by SDS-PAGE and visualized by silver stain.

References

1. Hamilton, G.S. and J.P. Steiner (1998) J. Med. Chem. 41:5119. \n2. Liu, J. et al. (1992) Biochemistry 31:3896. \n3. Toral-Barza, L. et al. (2005) Biochem. Biophys. Res. Comm. 332:304. \n4. Hamilton , S.L and M.M. Matzuk (1998) Nature 391:489.