1ihg: Difference between revisions

[[Image:1ihg.gif|left|200px]]<br /><applet load="1ihg" size="350" color="white" frame="true" align="right" spinBox="true"  

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.

1IHG is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Bos_taurus Bos taurus] with <scene name='pdbligand=GOL:'>GOL</scene> as [http://en.wikipedia.org/wiki/ligand ligand]. Active as [http://en.wikipedia.org/wiki/Peptidylprolyl_isomerase Peptidylprolyl isomerase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=5.2.1.8 5.2.1.8] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1IHG OCA].  

[[Category: Minchin, R F.]]

[[Category: Walkinshaw, M D.]]

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