View source for 5noj


==Ca2+-induced Movement of Tropomyosin on Native Cardiac Thin Filaments - "OPEN" state==
<SX load='5noj' size='340' side='right' viewer='molstar' caption='[[5noj]], [[Resolution|resolution]] 11.00&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[5noj]] is a 7 chain structure with sequence from [https://en.wikipedia.org/wiki/Sus_scrofa Sus scrofa]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=5NOJ OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=5NOJ FirstGlance]. <br>
</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">Electron Microscopy, [[Resolution|Resolution]] 11&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=ADP:ADENOSINE-5-DIPHOSPHATE'>ADP</scene>, <scene name='pdbligand=HIC:4-METHYL-HISTIDINE'>HIC</scene>, <scene name='pdbligand=MG:MAGNESIUM+ION'>MG</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=5noj FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=5noj OCA], [https://pdbe.org/5noj PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=5noj RCSB], [https://www.ebi.ac.uk/pdbsum/5noj PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=5noj ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/ACTS_PIG ACTS_PIG] Actins are highly conserved proteins that are involved in various types of cell motility and are ubiquitously expressed in all eukaryotic cells.
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
Muscle contraction relies on the interaction of myosin motors with F-actin, which is regulated through a translocation of tropomyosin by the troponin complex in response to Ca2+ The current model of muscle regulation holds that at relaxing (low-Ca2+) conditions tropomyosin blocks myosin binding sites on F-actin, whereas at activating (high-Ca2+) conditions tropomyosin translocation only partially exposes myosin binding sites on F-actin so that binding of rigor myosin is required to fully activate the thin filament (TF). Here we used a single-particle approach to helical reconstruction of frozen hydrated native cardiac TFs under relaxing and activating conditions to reveal the azimuthal movement of the tropomyosin on the surface of the native cardiac TF upon Ca2+ activation. We demonstrate that at either relaxing or activating conditions tropomyosin is not constrained in one structural state, but rather is distributed between three structural positions on the surface of the TF. We show that two of these tropomyosin positions restrain actomyosin interactions, whereas in the third position, which is significantly enhanced at high Ca2+, tropomyosin does not block myosin binding sites on F-actin. Our data provide a structural framework for the enhanced activation of the cardiac TF over the skeletal TF by Ca2+ and lead to a mechanistic model for the regulation of the cardiac TF.

Ca2+-induced movement of tropomyosin on native cardiac thin filaments revealed by cryoelectron microscopy.,Risi C, Eisner J, Belknap B, Heeley DH, White HD, Schroder GF, Galkin VE Proc Natl Acad Sci U S A. 2017 Jun 27;114(26):6782-6787. doi:, 10.1073/pnas.1700868114. Epub 2017 Jun 12. PMID:28607071<ref>PMID:28607071</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 5noj" style="background-color:#fffaf0;"></div>

==See Also==
*[[Actin 3D structures|Actin 3D structures]]
== References ==
<references/>
__TOC__
</SX>
[[Category: Large Structures]]
[[Category: Sus scrofa]]
[[Category: Belknap B]]
[[Category: Eisner J]]
[[Category: Galkin VE]]
[[Category: Heeley DH]]
[[Category: Risi C]]
[[Category: Schroeder GF]]
[[Category: White HD]]