title: Inhibition of calcineurin by a novel FK-506-binding protein.
abstract: FK-506, a potent immunosuppressive drug, acts during the commitment phase of T-lymphocyte activation to block a subset of calcium-associated events necessary for transcription of certain early lymphokine genes. The drug binds to an abundant, cytosolic 11.8-kDa protein termed the FK-506-binding protein (FKBP12). The FKBP12.FK-506 complex inhibits calcineurin, a calcium-dependent phosphatase that is a component of the signal transduction pathway leading to early lymphokine gene transcription. FKBP12 is one member of a growing gene family. Prior to this report, all other FKBP family members had been irrelevant to the mechanism of action of FK-506 because no other FKBP.FK-506 complexes were able to bind and inhibit calcineurin. Here, we report the purification and characterization of a novel FK-506-binding protein, FKBP12.6. Having 85% amino acid sequence identity to FKBP12, FKBP12.6 is, among the FKBPs, most closely related to FKBP12. When complexed with FK-506, FKBP12.6 binds to and inhibits calcineurin, making it only the second FKBP discovered thus far to do so. The ability to inhibit calcineurin establishes the potential relevance of FKBP12.6 to the immunosuppressive or toxic side effects of FK-506.
authors.affiliation: Department of Immunology Research, Merck Research Laboratories, Rahway, New Jersey 07065.
authors.forename: T J
authors.initials: TJ
authors.lastname: Sewell
authors.forename: E
authors.initials: E
authors.lastname: Lam
authors.forename: M M
authors.initials: MM
authors.lastname: Martin
authors.forename: J
authors.initials: J
authors.lastname: Leszyk
authors.forename: J
authors.initials: J
authors.lastname: Weidner
authors.forename: J
authors.initials: J
authors.lastname: Calaycay
authors.forename: P
authors.initials: P
authors.lastname: Griffin
authors.forename: H
authors.initials: H
authors.lastname: Williams
authors.forename: S
authors.initials: S
authors.lastname: Hung
authors.forename: J
authors.initials: J
authors.lastname: Cryan
mesh_terms: D000591:Amino Acid Isomerases / Q000037:antagonists & inhibitors; D000595:Amino Acid Sequence; D000818:Animals; D015153:Blotting, Western; D001921:Brain / Q000378:metabolism; D019703:Calcineurin; D002148:Calmodulin-Binding Proteins / Q000037:antagonists & inhibitors*; D002352:Carrier Proteins / Q000037:antagonists & inhibitors / Q000302:isolation & purification / Q000502:physiology*; D002417:Cattle; D003429:Cross Reactions; D004591:Electrophoresis, Polyacrylamide Gel; D006360:Heat-Shock Proteins / Q000302:isolation & purification / Q000502:physiology*; D008969:Molecular Sequence Data; D019696:Peptidylprolyl Isomerase; D010749:Phosphoprotein Phosphatases / Q000037:antagonists & inhibitors*; D011090:Polyenes / Q000494:pharmacology; D017386:Sequence Homology, Amino Acid; D020123:Sirolimus; D016559:Tacrolimus / Q000494:pharmacology*; D022021:Tacrolimus Binding Proteins
chemical_list: D002148:Calmodulin-Binding Proteins; D002352:Carrier Proteins; D006360:Heat-Shock Proteins; D011090:Polyenes; D019703:Calcineurin; D010749:Phosphoprotein Phosphatases; D000591:Amino Acid Isomerases; D022021:Tacrolimus Binding Proteins; D019696:Peptidylprolyl Isomerase; D020123:Sirolimus; D016559:Tacrolimus