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| | ==Solution structure of actin-binding domain of troponin in Ca2+-bound state== | | ==Solution structure of actin-binding domain of troponin in Ca2+-bound state== |
| - | <StructureSection load='1vdj' size='340' side='right' caption='[[1vdj]], [[NMR_Ensembles_of_Models | 20 NMR models]]' scene=''> | + | <StructureSection load='1vdj' size='340' side='right'caption='[[1vdj]]' scene=''> |
| | == Structural highlights == | | == Structural highlights == |
| - | <table><tr><td colspan='2'>[[1vdj]] is a 1 chain structure with sequence from [http://en.wikipedia.org/wiki/Chick Chick]. Full experimental information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1VDJ OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=1VDJ FirstGlance]. <br> | + | <table><tr><td colspan='2'>[[1vdj]] is a 1 chain structure with sequence from [https://en.wikipedia.org/wiki/Gallus_gallus Gallus gallus]. Full experimental information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1VDJ OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=1VDJ FirstGlance]. <br> |
| - | </td></tr><tr id='related'><td class="sblockLbl"><b>[[Related_structure|Related:]]</b></td><td class="sblockDat">[[1vdi|1vdi]]</td></tr> | + | </td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">Solution NMR</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=1vdj FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1vdj OCA], [http://pdbe.org/1vdj PDBe], [http://www.rcsb.org/pdb/explore.do?structureId=1vdj RCSB], [http://www.ebi.ac.uk/pdbsum/1vdj PDBsum], [http://prosat.h-its.org/prosat/prosatexe?pdbcode=1vdj ProSAT]</span></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=1vdj FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1vdj OCA], [https://pdbe.org/1vdj PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=1vdj RCSB], [https://www.ebi.ac.uk/pdbsum/1vdj PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=1vdj ProSAT]</span></td></tr> |
| | </table> | | </table> |
| | == Function == | | == Function == |
| - | [[http://www.uniprot.org/uniprot/TNNI2_CHICK TNNI2_CHICK]] Troponin I is the inhibitory subunit of troponin, the thin filament regulatory complex which confers calcium-sensitivity to striated muscle actomyosin ATPase activity. | + | [https://www.uniprot.org/uniprot/TNNI2_CHICK TNNI2_CHICK] Troponin I is the inhibitory subunit of troponin, the thin filament regulatory complex which confers calcium-sensitivity to striated muscle actomyosin ATPase activity. |
| | == Evolutionary Conservation == | | == Evolutionary Conservation == |
| | [[Image:Consurf_key_small.gif|200px|right]] | | [[Image:Consurf_key_small.gif|200px|right]] |
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| | ==See Also== | | ==See Also== |
| - | *[[Role of Troponin C in decreased muscle sensitivity to calcium|Role of Troponin C in decreased muscle sensitivity to calcium]]
| + | *[[Troponin 3D structures|Troponin 3D structures]] |
| - | *[[Troponin|Troponin]] | + | |
| | == References == | | == References == |
| | <references/> | | <references/> |
| | __TOC__ | | __TOC__ |
| | </StructureSection> | | </StructureSection> |
| - | [[Category: Chick]] | + | [[Category: Gallus gallus]] |
| - | [[Category: Murakami, K]] | + | [[Category: Large Structures]] |
| - | [[Category: Ohki, S]] | + | [[Category: Murakami K]] |
| - | [[Category: Tanokura, M]] | + | [[Category: Ohki S]] |
| - | [[Category: Wakabayashi, T]] | + | [[Category: Tanokura M]] |
| - | [[Category: Yasunaga, T]] | + | [[Category: Wakabayashi T]] |
| - | [[Category: Yumoto, F]] | + | [[Category: Yasunaga T]] |
| - | [[Category: Actin]]
| + | [[Category: Yumoto F]] |
| - | [[Category: Contractile protein]]
| + | |
| - | [[Category: Tropomyosin]]
| + | |
| - | [[Category: Troponin]]
| + | |
| Structural highlights
Function
TNNI2_CHICK Troponin I is the inhibitory subunit of troponin, the thin filament regulatory complex which confers calcium-sensitivity to striated muscle actomyosin ATPase activity.
Evolutionary Conservation
Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf.
Publication Abstract from PubMed
Troponin and tropomyosin on actin filaments constitute a Ca2+-sensitive switch that regulates the contraction of vertebrate striated muscle through a series of conformational changes within the actin-based thin filament. Troponin consists of three subunits: an inhibitory subunit (TnI), a Ca2+-binding subunit (TnC), and a tropomyosin-binding subunit (TnT). Ca2+-binding to TnC is believed to weaken interactions between troponin and actin, and triggers a large conformational change of the troponin complex. However, the atomic details of the actin-binding sites of troponin have not been determined. Ternary troponin complexes have been reconstituted from recombinant chicken skeletal TnI, TnC, and TnT2 (the C-terminal region of TnT), among which only TnI was uniformly labelled with 15N and/or 13C. By applying NMR spectroscopy, the solution structures of a "mobile" actin-binding domain (approximately 6.1 kDa) in the troponin ternary complex (approximately 52 kDa) were determined. The mobile domain appears to tumble independently of the core domain of troponin. Ca2+-induced changes in the chemical shift and line shape suggested that its tumbling was more restricted at high Ca2+ concentrations. The atomic details of interactions between actin and the mobile domain of troponin were defined by docking the mobile domain into the cryo-electron microscopy (cryo-EM) density map of thin filament at low [Ca2+]. This allowed the determination of the 3D position of residue 133 of TnI, which has been an important landmark to incorporate the available information. This enabled unique docking of the entire globular head region of troponin into the thin filament cryo-EM map at a low Ca2+ concentration. The resultant atomic model suggests that troponin interacted electrostatically with actin and caused the shift of tropomyosin to achieve muscle relaxation. An important feature is that the coiled-coil region of troponin pushed tropomyosin at a low Ca2+ concentration. Moreover, the relationship between myosin and the mobile domain on actin filaments suggests that the latter works as a fail-safe latch.
Structural basis for Ca2+-regulated muscle relaxation at interaction sites of troponin with actin and tropomyosin.,Murakami K, Yumoto F, Ohki SY, Yasunaga T, Tanokura M, Wakabayashi T J Mol Biol. 2005 Sep 9;352(1):178-201. PMID:16061251[1]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
See Also
References
- ↑ Murakami K, Yumoto F, Ohki SY, Yasunaga T, Tanokura M, Wakabayashi T. Structural basis for Ca2+-regulated muscle relaxation at interaction sites of troponin with actin and tropomyosin. J Mol Biol. 2005 Sep 9;352(1):178-201. PMID:16061251 doi:10.1016/j.jmb.2005.06.067
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