View source for 1uhk


==Crystal structure of n-aequorin==
<StructureSection load='1uhk' size='340' side='right'caption='[[1uhk]], [[Resolution|resolution]] 1.60&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[1uhk]] is a 2 chain structure with sequence from [https://en.wikipedia.org/wiki/Aequorea_victoria Aequorea victoria]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1UHK OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=1UHK FirstGlance]. <br>
</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 1.6&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=CZN:(2S,8R)-8-BENZYL-2-HYDROPEROXY-6-(4-HYDROXYPHENYL)-2-(2-NAPHTHYLMETHYL)-7,8-DIHYDROIMIDAZO[1,2-A]PYRAZIN-3(2H)-ONE'>CZN</scene></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=1uhk FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1uhk OCA], [https://pdbe.org/1uhk PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=1uhk RCSB], [https://www.ebi.ac.uk/pdbsum/1uhk PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=1uhk ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/AEQ2_AEQVI AEQ2_AEQVI] Ca(2+)-dependent bioluminescence photoprotein. Displays an emission peak at 470 nm (blue light). Trace amounts of calcium ion trigger the intramolecular oxidation of the chromophore, coelenterazine into coelenteramide and CO(2) with the concomitant emission of light.
== 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/uh/1uhk_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=1uhk ConSurf].
<div style="clear:both"></div>
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
The photoprotein aequorin emits light by an intramolecular reaction in the presence of a trace amount of Ca(2+). Semi-synthetic aequorins, produced by replacing the coelenterazine moiety in aequorin with the analogues of coelenterazine, show widely different sensitivities to Ca(2+). To understand the structural basis of the Ca(2+)-sensitivity, we determined the crystal structures of four semi-synthetic aequorins (cp-, i-, br- and n-aequorins) at resolutions of 1.6-1.8 A. In general, the protein structures of these semi-synthetic aequorins are almost identical to native aequorin. Of the four EF-hand domains in the molecule, EF-hand II does not bind Ca(2+), and the loop of EF-hand IV is clearly deformed. It is most likely that the binding of Ca(2+) with EF-hands I and III triggers luminescence. Although little difference was found in the overall structures of aequorins investigated, some significant differences were found in the interactions between the substituents of coelenterazine moiety and the amino acid residues in the binding pocket. The coelenterazine moieties in i-, br-, and n-aequorins have bulky 2-substitutions, which can interfere with the conformational changes of protein structure that follow the binding of Ca(2+) to aequorin. In cp-aequorin, the cyclopentylmethyl group that substitutes for the original 8-benzyl group does not interact hydrophobically with the protein part, giving the coelenterazine moiety more conformational freedom to promote the light-emitting reaction. The differences of various semi-synthetic aequorins in Ca(2+)-sensitivity and reaction rate are explained by the capability of the involved groups and structures to undergo conformational changes in response to the Ca(2+)-binding.

The crystal structures of semi-synthetic aequorins.,Toma S, Chong KT, Nakagawa A, Teranishi K, Inouye S, Shimomura O Protein Sci. 2005 Feb;14(2):409-16. Epub 2005 Jan 4. PMID:15632284<ref>PMID:15632284</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 1uhk" style="background-color:#fffaf0;"></div>
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Aequorea victoria]]
[[Category: Large Structures]]
[[Category: Chong KT]]
[[Category: Inouye S]]
[[Category: Nakagawa A]]
[[Category: Shimomura O]]
[[Category: Teranishi K]]
[[Category: Toma S]]