1fkl: Difference between revisions

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

FK506 (tacrolimus) is a natural product now approved in the US and Japan for organ transplantation. FK506, in complex with its 12 kDa cytosolic receptor (FKBP12), is a potent agonist of immunosuppression through the inhibition of the phosphatase activity of calcineurin. Rapamycin (sirolimus), which is itself an immunosuppressant by a different mechanism, completes with FK506 for binding to FKBP12 and thereby acts as an antagonist of calcineurin inhibition. We have solved the X-ray structure of unliganded FKBP12 and of FKBP12 in complex with FK506 and with rapamycin; these structures show localized differences in conformation and mobility in those regions of the protein that are known, by site-directed mutagenesis, to be involved in calcineurin inhibition. A comparison of 16 additional X-ray structures of FKBP12 in complex with FKBP12-binding ligands, where those structures were determined from different crystal forms with distinct packing arrangements, lends significance to the observed structural variability and suggests that it represents an intrinsic functional characteristic of the protein. Similar differences have been observed for FKBP12 before, but were considered artifacts of crystal-packing interactions. We suggest that immunosuppressive ligands express their differential effects in part by modulating the conformation of FKBP12, in agreement with mutagenesis experiments on the protein, and not simply through differences in the ligand structures themselves.

1FKL 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=RAP:'>RAP</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=1FKL OCA].  

[[Category: Navia, M A.]]

[[Category: Sintchak, M D.]]

[[Category: Thomson, J A.]]

[[Category: Wilson, K P.]]

''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 12:39:38 2008''