1npq

<StructureSection load='1npq' size='340' side='right'caption='[[1npq]], [[NMR_Ensembles_of_Models | 21 NMR models]]' scene=''>

<table><tr><td colspan='2'>[[1npq]] is a 2 chain structure with sequence from [https://en.wikipedia.org/wiki/Chick Chick]. Full experimental information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1NPQ OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=1NPQ 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='gene'><td class="sblockLbl"><b>[[Gene|Gene:]]</b></td><td class="sblockDat">TNNC2 ([https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=9031 CHICK])</td></tr>

[[https://www.uniprot.org/uniprot/TNNC2_CHICK TNNC2_CHICK]] 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. [[https://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.

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== Publication Abstract from PubMed ==

The structure of the calcium-saturated regulatory domain of skeletal troponin C (sNTnC) complexed with the switch peptide comprising residues 115-131 of troponin I (TnI), and with a bifunctional rhodamine fluorescent label attached to residues 56 (E56C) and 63 (E63C) on the C helix of sNTnC, has been determined using nuclear magnetic resonance (NMR) spectroscopy. The structure shows that the integrity of the C helix is not altered by the E(56,63)C mutations or by the presence of the bifunctional rhodamine and that the label does not interact with the hydrophobic cleft of sNTnC. Moreover, the overall fold of the protein and the position of the TnI peptide are similar to those observed previously with related cardiac NTnC complexes with residues 147-163 of cardiac TnI [Li et al. (1999) Biochemistry 38, 8289-8298] and including the drug bepridil [Wang et al. (2002) J. Biol. Chem. 277, 31124-31133]. The degree of opening of the structure is reduced as compared to that of calcium-saturated sNTnC in the absence of the switch peptide [Gagne et al. (1995) Nat. Struct. Biol. 2, 784-789]. The switch peptide is bound in a shallow and complementary hydrophobic surface cleft largely defined by helices A and B and also has key ionic interactions with sNTnC. These results show that bifunctional rhodamine probes can be attached to surface helices via suitable pairs of solvent-accessible residues that have been mutated to cysteines, without altering the conformation of the labeled domain. A set of such probes can be used to determine the orientation and motion of the target domain in the cellular environment [Corrie et al. (1999) Nature 400, 425-430; Ferguson et al. (2003) Mol. Cell 11(4), in press].

NMR structure of a bifunctional rhodamine labeled N-domain of troponin C complexed with the regulatory "switch" peptide from troponin I: implications for in situ fluorescence studies in muscle fibers.,Mercier P, Ferguson RE, Irving M, Corrie JE, Trentham DR, Sykes BD Biochemistry. 2003 Apr 22;42(15):4333-48. PMID:12693929<ref>PMID:12693929</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 1npq" style="background-color:#fffaf0;"></div>

*[[Troponin|Troponin]]

[[Category: Chick]]

[[Category: Corrie, J E.T]]

[[Category: Ferguson, R E]]

[[Category: Irving, M]]

[[Category: Mercier, P]]

[[Category: Sykes, B D]]

[[Category: Trentham, D R]]

[[Category: Troponin c- troponin i complex]]