title: Molecular cloning of a 25-kDa high affinity rapamycin binding protein, FKBP25.
abstract: Two FK506 binding proteins of molecular mass 12 kDa (FKBP12) and 13 kDa (FKBP13) have been identified as common cellular receptors of the immunosuppressants FK506 and rapamycin. Here we report the molecular cloning and overexpression of a 25-kDa rapamycin and FK506 binding protein (termed FKBP25) with peptidylprolyl cis-trans-isomerase (PPIase) activity. The amino acid sequence, predicted from the FKBP25 cDNA, shares identity with FKBP12 (44%) and FKBP13 (47%) in the C-terminal 97 amino acids. Unlike either FKBP12 or FKBP13, the nucleotide sequence of FKBP25 contains a number of putative nuclear localization sequences. The PPIase activity of recombinant FKBP25 was comparable with that of FKBP12. The PPIase activity of FKBP25 was far more sensitive to inhibition by rapamycin (IC50 = 50 nM) than FK506 (IC50 = 400 nM). PPIase activity of 100 nM FKBP25 was almost completely inhibited by 150 nM rapamycin while only 90% inhibition was achieved by 4 microM FK506. These data demonstrate that FKBP25 has a higher affinity for rapamycin than for FK506 and suggest that this cellular receptor may be an important target molecule for immunosuppression by rapamycin.
authors.affiliation: Division of Pediatric Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts.
authors.forename: Y J
authors.initials: YJ
authors.lastname: Jin
authors.forename: S J
authors.initials: SJ
authors.lastname: Burakoff
authors.forename: B E
authors.initials: BE
authors.lastname: Bierer
mesh_terms: D000591:Amino Acid Isomerases / Q000037:antagonists & inhibitors / Q000378:metabolism; D000595:Amino Acid Sequence; D001483:Base Sequence; D015152:Blotting, Northern; D002352:Carrier Proteins / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism; D003001:Cloning, Molecular; D004247:DNA / Q000235:genetics; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000378:metabolism; D006360:Heat-Shock Proteins / Q000235:genetics*; D006801:Humans; D008969:Molecular Sequence Data; D019696:Peptidylprolyl Isomerase; D012313:RNA / Q000235:genetics; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D012689:Sequence Homology, Nucleic Acid; D013379:Substrate Specificity; D022021:Tacrolimus Binding Proteins
chemical_list: D002352:Carrier Proteins; D006360:Heat-Shock Proteins; D011994:Recombinant Proteins; C074856:FKBP3 protein, human; D012313:RNA; D004247:DNA; D000591:Amino Acid Isomerases; D022021:Tacrolimus Binding Proteins; D019696:Peptidylprolyl Isomerase