1ihg
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Bovine Cyclophilin 40, monoclinic form
OverviewOverview
BACKGROUND: The "large immunophilin" family consists of domains of, cyclophilin or FK506 binding protein linked to a tetratricopeptide (TPR), domain. They are intimately associated with steroid receptor complexes and, bind to the C-terminal domain of Hsp90 via the TPR domain. The competitive, binding of specific large immunophilins and other TPR-Hsp90 proteins, provides a regulatory mechanism for Hsp90 chaperone activity. RESULTS: We, have solved the X-ray structures of monoclinic and tetragonal forms of, Cyp40. In the monoclinic form, the TPR domain consists of seven helices of, variable length incorporating three TPR motifs, which provide a convincing, binding surface for the Hsp90 C-terminal MEEVD sequence. The C-terminal, residues of Cyp40 protrude out beyond the body of the TPR domain to form a, charged helix-the putative calmodulin binding site. However, in the, tetragonal form, two of the TPR helices have straightened out to form one, extended helix, providing a dramatically different conformation of the, molecule. CONCLUSIONS: The X-ray structures are consistent with the role, of Cyclophilin 40 as a multifunctional signaling protein involved in a, variety of protein-protein interactions. The intermolecular helix-helix, interactions in the tetragonal form mimic the intramolecular interactions, found in the fully folded monoclinic form. These conserved intra- and, intermolecular TPR-TPR interactions are illustrative of a high-fidelity, recognition mechanism. The two structures also open up the possibility, that partially folded forms of TPR may be important in domain swapping and, protein recognition.
About this StructureAbout this Structure
1IHG is a Single protein structure of sequence from Bos taurus with GOL as ligand. Active as Peptidylprolyl isomerase, with EC number 5.2.1.8 Full crystallographic information is available from OCA.
ReferenceReference
Two structures of cyclophilin 40: folding and fidelity in the TPR domains., Taylor P, Dornan J, Carrello A, Minchin RF, Ratajczak T, Walkinshaw MD, Structure. 2001 May 9;9(5):431-8. PMID:11377203
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