5tnc

<table><tr><td colspan='2'>[[5tnc]] is a 1 chain structure with sequence from [http://en.wikipedia.org/wiki/Melga Melga]. This structure supersedes the now removed PDB entry [http://oca.weizmann.ac.il/oca-bin/send-pdb?obs=1&id=2tnc 2tnc]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=5TNC OCA]. For a <b>guided tour on the structure components</b> use [http://proteopedia.org/fgij/fg.htm?mol=5TNC FirstGlance]. <br>

</td></tr><tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><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://proteopedia.org/fgij/fg.htm?mol=5tnc FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=5tnc OCA], [http://pdbe.org/5tnc PDBe], [http://www.rcsb.org/pdb/explore.do?structureId=5tnc RCSB], [http://www.ebi.ac.uk/pdbsum/5tnc PDBsum], [http://prosat.h-its.org/prosat/prosatexe?pdbcode=5tnc ProSAT]</span></td></tr>

[[http://www.uniprot.org/uniprot/TNNC2_MELGA TNNC2_MELGA]] 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.

<div style="background-color:#fffaf0;">

== Publication Abstract from PubMed ==

The crystal structure of troponin C from turkey skeletal muscle has been refined at 2.0 A resolution (1 A = 0.1 nm). The resulting crystallographic R factor (R = sigma[[Fo[-[Fc[[/sigma[Fo[, where [Fo[ and [Fc[ are the observed and calculated structure factor amplitudes) is 0.155 for the 8054 reflections with intensities I greater than or equal to 2 sigma(I) within the 10 A to 2.0 A resolution range. With 66% of the residues in helical conformation, troponin C provides a good sample for helix analysis. The mean alpha-helix dihedral angles (phi, psi = -62 degrees, -42 degrees) agree with values observed for helical regions in other proteins. The helices are all curved and/or kinked. In particular, the 31 amino acid long inter-domain helix is smoothly curved, with a rather large radius of curvature of 137 A. Helix packing is different in the Ca2+-free domain (N-terminal) and the Ca2+-bound domain (C-terminal). The inter-helix angles for the two helix-loop-helix motifs in the regulatory domain are 133 degrees and 151 degrees, whereas the value for the two motifs in the C-terminal domain is 110 degrees, as observed in the EF-hands of parvalbumin. These differences affect the packing of the respective hydrophobic cores of each domain, in particular the disposition of aromatic rings. Pairwise arrangement of Ca2+-binding loops is common to both states, but the conformation is markedly different. Conversion of one to the other can be achieved by small cumulative changes of main-chain dihedral angles. The integrity of loop structure is maintained by numerous electrostatic interactions. Both salt bridges and carboxyl-carboxylate interactions are observed in TnC. There are more intramolecular (9) than intermolecular (1) salt bridges. Carboxyl-carboxylate interactions occur because the pH of the crystals is 5.0 and there is a multitude of aspartate and glutamate residues. One is intramolecular and four are intermolecular. Polar side-chain interactions occur more commonly with main-chain carbonyls and amides than with other polar side-chains. These interactions are mostly short range, and are similar to those observed in other proteins with one exception: negatively charged side-chains interact more frequently with main-chain carbonyl oxygen atoms. However, out of 19 such interactions, 10 involve oxygen atoms of the Ca2+ ligands. These unfavorable interactions are compensated by the favorable interactions with the Ca2+ ions and with main-chain amides. They are a trivial consequence of the tight fold of the Ca2+-binding loops.

Refined crystal structure of troponin C from turkey skeletal muscle at 2.0 A resolution.,Herzberg O, James MN J Mol Biol. 1988 Oct 5;203(3):761-79. PMID:3210231<ref>PMID:3210231</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>

</div>

<div class="pdbe-citations 5tnc" style="background-color:#fffaf0;"></div>

*[[Troponin|Troponin]]

[[Category: Melga]]

[[Category: Herzberg, O]]

[[Category: James, M N.G]]

[[Category: Contractile system protein]]