FKBP13: Proteins and Enzymes

FK506 binding protein, 13 kilodalton molecular weight (FKBP13), also called FKBP2, is a peptidyl-prolyl isomerase that catalyzes the transition between cis- and trans-proline residues critical for proper folding of proteins. The immunosuppressants FK506 and rapamycin are potent inhibitors of FKBP13. This isomerase is localized in the endoplasmic reticulum and is also associated with cytoskeletal elements such as erythrocyte band 4.1. FKBP13 levels are increased by treatments that affect golgi protein processing such as tunicamycin and heat shock, suggesting that FKBP13 is important in the unfolded protein response observed with endoplasmic reticulum stress.