1a2x

<StructureSection load='1a2x' size='340' side='right' caption='[[1a2x]], [[Resolution|resolution]] 2.30&Aring;' scene=''>

<table><tr><td colspan='2'>[[1a2x]] is a 2 chain structure with sequence from [http://en.wikipedia.org/wiki/European_rabbit European rabbit]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1A2X OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=1A2X FirstGlance]. <br>

</td></tr><tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat"><scene name='pdbligand=CA:CALCIUM+ION'>CA</scene></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=1a2x FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1a2x OCA], [http://pdbe.org/1a2x PDBe], [http://www.rcsb.org/pdb/explore.do?structureId=1a2x RCSB], [http://www.ebi.ac.uk/pdbsum/1a2x PDBsum]</span></td></tr>

[[http://www.uniprot.org/uniprot/TNNC2_RABIT TNNC2_RABIT]] Troponin is the central regulatory protein of striated muscle contraction. Tn consists of three components: Tn-I which is the inhibitor of actomyosin ATPase, Tn-T which contains the binding site for tropomyosin and Tn-C. The binding of calcium to Tn-C abolishes the inhibitory action of Tn on actin filaments. [[http://www.uniprot.org/uniprot/TNNI2_RABIT TNNI2_RABIT]] Troponin I is the inhibitory subunit of troponin, the thin filament regulatory complex which confers calcium-sensitivity to striated muscle actomyosin ATPase activity.

<scriptWhenChecked>select protein; define ~consurf_to_do selected; consurf_initial_scene = true; script "/wiki/ConSurf/a2/1a2x_consurf.spt"</scriptWhenChecked>

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== Publication Abstract from PubMed ==

Troponin (Tn), the complex of three subunits (TnC, TnI, and TnT), plays a key role in Ca2+-dependent regulation of muscle contraction. To elucidate the interactions between the Tn subunits and the conformation of TnC in the Tn complex, we have determined the crystal structure of TnC (two Ca2+ bound state) in complex with the N-terminal fragment of TnI (TnI1-47). The structure was solved by the single isomorphous replacement method in combination with multiple wavelength anomalous dispersion data. The refinement converged to a crystallographic R factor of 22.2% (Rfree = 32.6%). The central, connecting alpha-helix observed in the structure of uncomplexed TnC (TnCfree) is unwound at the center (residues Ala-87, Lys-88, Gly-89, Lys-90, and Ser-91) and bent by 90 degrees. As a result, TnC in the complex has a compact globular shape with direct interactions between the N- and C-terminal lobes, in contrast to the elongated dumb-bell shaped molecule of uncomplexed TnC. The 31-residue long TnI1-47 alpha-helix stretches on the surface of TnC and stabilizes its compact conformation by multiple contacts with both TnC lobes. The amphiphilic C-end of the TnI1-47 alpha-helix is bound in the hydrophobic pocket of the TnC C-lobe through 38 van der Waals interactions. The results indicate the major difference between Ca2+ receptors integrated with the other proteins (TnC in Tn) and isolated in the cytosol (calmodulin). The TnC/TnI1-47 structure implies a mechanism of how Tn regulates the muscle contraction and suggests a unique alpha-helical regulatory TnI segment, which binds to the N-lobe of TnC in its Ca2+ bound conformation.

Crystal structure of troponin C in complex with troponin I fragment at 2.3-A resolution.,Vassylyev DG, Takeda S, Wakatsuki S, Maeda K, Maeda Y Proc Natl Acad Sci U S A. 1998 Apr 28;95(9):4847-52. PMID:9560191<ref>PMID:9560191</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 1a2x" style="background-color:#fffaf0;"></div>

*[[Role of Troponin C in decreased muscle sensitivity to calcium|Role of Troponin C in decreased muscle sensitivity to calcium]]

[[Category: European rabbit]]

[[Category: Maeda, K]]

[[Category: Maeda, Y]]

[[Category: Takeda, S]]

[[Category: Vassylyev, D G]]

[[Category: Wakatsuki, S]]

[[Category: Troponin]]