View source for 1icf


==CRYSTAL STRUCTURE OF MHC CLASS II ASSOCIATED P41 II FRAGMENT IN COMPLEX WITH CATHEPSIN L==
<StructureSection load='1icf' size='340' side='right'caption='[[1icf]], [[Resolution|resolution]] 2.00&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[1icf]] is a 6 chain structure with sequence from [http://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1ICF OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=1ICF FirstGlance]. <br>
</td></tr><tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat"><scene name='pdbligand=NAG:N-ACETYL-D-GLUCOSAMINE'>NAG</scene></td></tr>
<tr id='activity'><td class="sblockLbl"><b>Activity:</b></td><td class="sblockDat"><span class='plainlinks'>[http://en.wikipedia.org/wiki/Cathepsin_L Cathepsin L], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.4.22.15 3.4.22.15] </span></td></tr>
<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=1icf FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1icf OCA], [http://pdbe.org/1icf PDBe], [http://www.rcsb.org/pdb/explore.do?structureId=1icf RCSB], [http://www.ebi.ac.uk/pdbsum/1icf PDBsum], [http://prosat.h-its.org/prosat/prosatexe?pdbcode=1icf ProSAT]</span></td></tr>
</table>
== Disease ==
[[http://www.uniprot.org/uniprot/HG2A_HUMAN HG2A_HUMAN]] Note=A chromosomal aberration involving CD74 is found in a non-small cell lung tumor. Results in the formation of a CD74-ROS1 chimeric protein.<ref>PMID:12661006</ref>  
== Function ==
[[http://www.uniprot.org/uniprot/CATL1_HUMAN CATL1_HUMAN]] Important for the overall degradation of proteins in lysosomes. [[http://www.uniprot.org/uniprot/HG2A_HUMAN HG2A_HUMAN]] Plays a critical role in MHC class II antigen processing by stabilizing peptide-free class II alpha/beta heterodimers in a complex soon after their synthesis and directing transport of the complex from the endoplasmic reticulum to the endosomal/lysosomal system where the antigen processing and binding of antigenic peptides to MHC class II takes place. Serves as cell surface receptor for the cytokine MIF. 
== Evolutionary Conservation ==
[[Image:Consurf_key_small.gif|200px|right]]
Check<jmol>
  <jmolCheckbox>
    <scriptWhenChecked>; select protein; define ~consurf_to_do selected; consurf_initial_scene = true; script "/wiki/ConSurf/ic/1icf_consurf.spt"</scriptWhenChecked>
    <scriptWhenUnchecked>script /wiki/extensions/Proteopedia/spt/initialview01.spt</scriptWhenUnchecked>
    <text>to colour the structure by Evolutionary Conservation</text>
  </jmolCheckbox>
</jmol>, as determined by [http://consurfdb.tau.ac.il/ ConSurfDB]. You may read the [[Conservation%2C_Evolutionary|explanation]] of the method and the full data available from [http://bental.tau.ac.il/new_ConSurfDB/main_output.php?pdb_ID=1icf ConSurf].
<div style="clear:both"></div>
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
The lysosomal cysteine proteases cathepsins S and L play crucial roles in the degradation of the invariant chain during maturation of MHC class II molecules and antigen processing. The p41 form of the invariant chain includes a fragment which specifically inhibits cathepsin L but not S. The crystal structure of the p41 fragment, a homologue of the thyroglobulin type-1 domains, has been determined at 2.0 A resolution in complex with cathepsin L. The structure of the p41 fragment demonstrates a novel fold, consisting of two subdomains, each stabilized by disulfide bridges. The first subdomain is an alpha-helix-beta-strand arrangement, whereas the second subdomain has a predominantly beta-strand arrangement. The wedge shape and three-loop arrangement of the p41 fragment bound to the active site cleft of cathepsin L are reminiscent of the inhibitory edge of cystatins, thus demonstrating the first example of convergent evolution observed in cysteine protease inhibitors. However, the different fold of the p41 fragment results in additional contacts with the top of the R-domain of the enzymes, which defines the specificity-determining S2 and S1' substrate-binding sites. This enables inhibitors based on the thyroglobulin type-1 domain fold, in contrast to the rather non-selective cystatins, to exhibit specificity for their target enzymes.

Crystal structure of MHC class II-associated p41 Ii fragment bound to cathepsin L reveals the structural basis for differentiation between cathepsins L and S.,Guncar G, Pungercic G, Klemencic I, Turk V, Turk D EMBO J. 1999 Feb 15;18(4):793-803. PMID:10022822<ref>PMID:10022822</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
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<div class="pdbe-citations 1icf" style="background-color:#fffaf0;"></div>

==See Also==
*[[Cathepsin 3D structures|Cathepsin 3D structures]]
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Cathepsin L]]
[[Category: Homo sapiens]]
[[Category: Large Structures]]
[[Category: Guncar, G]]
[[Category: Klemencic, I]]
[[Category: Pungercic, G]]
[[Category: Turk, D]]
[[Category: Turk, V]]
[[Category: Cathepsin]]
[[Category: Cysteine proteinase]]
[[Category: Hydrolase]]
[[Category: Invariant chain]]
[[Category: Mhc class ii]]
[[Category: Thyroglobulin type-1 domain]]