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Structure of the large FK506-binding protein FKBP51, an Hsp90-binding protein and a component of steroid receptor complexes.

The ability to bind immunosuppressive drugs such as cyclosporin and FK506 defines the immunophilin family of proteins, and the FK506-binding proteins form the FKBP subfamily of immunophilins. Some FKBPs, notably FKBP12 (the 12-kDa FK506-binding protein), have defined roles in regulating ion channels or cell signaling, and well established structures. Other FKBPs, especially the larger ones, participate in important biological processes, but their exact roles and the structural bases for these roles are poorly defined. FKBP51 (the 51-kDa FKBP) associates with heat shock protein 90 (Hsp90) and appears in functionally mature steroid receptor complexes. In New World monkeys, FKBP51 has been implicated in cortisol resistance. We report here the x-ray structures of human FKBP51, to 2.7 A, and squirrel monkey FKBP51, to 2.8 A, by using multiwavelength anomalous dispersion phasing. FKBP51 is composed of three domains: two consecutive FKBP domains and a three-unit repeat of the TPR (tetratricopeptide repeat) domain. This structure of a multi-FKBP domain protein clarifies the arrangement of these domains and their possible interactions with other proteins. The two FKBP domains differ by an insertion in the second that affects the formation of the progesterone receptor complex.

Pubmed ID: 12538866


  • Sinars CR
  • Cheung-Flynn J
  • Rimerman RA
  • Scammell JG
  • Smith DF
  • Clardy J


Proceedings of the National Academy of Sciences of the United States of America

Publication Data

February 4, 2003

Associated Grants

  • Agency: NCI NIH HHS, Id: R01 CA59021
  • Agency: NIDDK NIH HHS, Id: R01 DK48218
  • Agency: NCRR NIH HHS, Id: RR-01646
  • Agency: NCRR NIH HHS, Id: RR-13200

Mesh Terms

  • Animals
  • Binding Sites
  • Conserved Sequence
  • Crystallography, X-Ray
  • Gene Deletion
  • Glucocorticoids
  • HSP90 Heat-Shock Proteins
  • Humans
  • Models, Molecular
  • Mutagenesis, Site-Directed
  • Protein Binding
  • Protein Structure, Tertiary
  • Receptors, Progesterone
  • Saimiri
  • Tacrolimus Binding Proteins