1sji: Difference between revisions

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-[[Image:1sji.gif|left|200px]]<br /><applet load="1sji" size="350" color="white" frame="true" align="right" spinBox="true"
-caption="1sji, resolution 2.4&Aring;" />
-'''Comparing skeletal and cardiac calsequestrin structures and their calcium binding: a proposed mechanism for coupled calcium binding and protein polymerization'''<br />
-==Overview==
+==Comparing skeletal and cardiac calsequestrin structures and their calcium binding: a proposed mechanism for coupled calcium binding and protein polymerization==
-Calsequestrin, the major calcium storage protein of both cardiac and skeletal muscle, binds and releases large numbers of Ca(2+) ions for each contraction and relaxation cycle. Here we show that two crystal structures for skeletal and cardiac calsequestrin are nearly superimposable not only for their subunits but also their front-to-front-type dimers. Ca(2+) binding curves were measured using atomic absorption spectroscopy. This method enables highly accurate measurements even for Ca(2+) bound to polymerized protein. The binding curves for both skeletal and cardiac calsequestrin were complex, with binding increases that correlated with protein dimerization, tetramerization, and oligomerization. The Ca(2+) binding capacities of skeletal and cardiac calsequestrin are directly compared for the first time, with approximately 80 Ca(2+) ions bound per skeletal calsequestrin and approximately 60 Ca(2+) ions per cardiac calsequestrin, as compared with net charges for these molecules of -80 and -69, respectively. Deleting the negatively charged and disordered C-terminal 27 amino acids of cardiac calsequestrin results in a 50% reduction of its calcium binding capacity and a loss of Ca(2+)-dependent tetramer formation. Based on the crystal structures of rabbit skeletal muscle calsequestrin and canine cardiac calsequestrin, Ca(2+) binding capacity data, and previous light-scattering data, a mechanism of Ca(2+) binding coupled with polymerization is proposed.
+<StructureSection load='1sji' size='340' side='right'caption='[[1sji]], [[Resolution|resolution]] 2.40&Aring;' scene=''>
+== Structural highlights ==
-==About this Structure==
+<table><tr><td colspan='2'>[[1sji]] is a 2 chain structure with sequence from [https://en.wikipedia.org/wiki/Canis_lupus_familiaris Canis lupus familiaris]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1SJI OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=1SJI FirstGlance]. <br>
-SJI is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Canis_lupus_familiaris Canis lupus familiaris]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1SJI OCA].
+</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 2.4&#8491;</td></tr>
+<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=1sji FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1sji OCA], [https://pdbe.org/1sji PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=1sji RCSB], [https://www.ebi.ac.uk/pdbsum/1sji PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=1sji ProSAT]</span></td></tr>
-==Reference==
+</table>
-Comparing skeletal and cardiac calsequestrin structures and their calcium binding: a proposed mechanism for coupled calcium binding and protein polymerization., Park H, Park IY, Kim E, Youn B, Fields K, Dunker AK, Kang C, J Biol Chem. 2004 Apr 23;279(17):18026-33. Epub 2004 Feb 10. PMID:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=14871888 14871888]
+== Function ==
+[https://www.uniprot.org/uniprot/CASQ2_CANLF CASQ2_CANLF] Calsequestrin is a high-capacity, moderate affinity, calcium-binding protein and thus acts as an internal calcium store in muscle (PubMed:3427023). Calcium ions are bound by clusters of acidic residues at the protein surface, especially at the interface between subunits. Can bind around 60 Ca(2+) ions. Regulates the release of lumenal Ca(2+) via the calcium release channel RYR2; this plays an important role in triggering muscle contraction. Plays a role in excitation-contraction coupling in the heart and in regulating the rate of heart beats.<ref>PMID:14871888</ref> <ref>PMID:20302875</ref> <ref>PMID:3427023</ref>
+== 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/sj/1sji_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=1sji ConSurf].
+<div style="clear:both"></div>
+== References ==
+<references/>
+__TOC__
+</StructureSection>
 [[Category: Canis lupus familiaris]]
-[[Category: Single protein]]
+[[Category: Large Structures]]
-[[Category: Dunker, A K.]]
+[[Category: Dunker AK]]
-[[Category: Fields, K.]]
+[[Category: Fields K]]
-[[Category: Kang, C H.]]
+[[Category: Kang CH]]
-[[Category: Kim, E J.]]
+[[Category: Kim EJ]]
-[[Category: Park, H J.]]
+[[Category: Park HJ]]
-[[Category: Park, I Y.]]
+[[Category: Park IY]]
-[[Category: Youn, B.]]
+[[Category: Youn B]]
-[[Category: calcium-binding]]
-[[Category: calsequestrin]]
-[[Category: glycoprotein]]
-[[Category: muscle protein]]
-''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 15:02:07 2008''