View source for 8dd0


==The structure of the native cardiac thin filament junction region==
<StructureSection load='8dd0' size='340' side='right'caption='[[8dd0]], [[Resolution|resolution]] 3.50&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[8dd0]] is a 16 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=8DD0 OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=8DD0 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]] 3.5&#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=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=8dd0 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=8dd0 OCA], [https://pdbe.org/8dd0 PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=8dd0 RCSB], [https://www.ebi.ac.uk/pdbsum/8dd0 PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=8dd0 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.
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== Publication Abstract from PubMed ==
Cardiac contraction depends on molecular interactions among sarcomeric proteins coordinated by the rising and falling intracellular Ca(2+) levels. Cardiac thin filament (cTF) consists of two strands composed of actin, tropomyosin (Tm), and equally spaced troponin (Tn) complexes forming regulatory units. Tn binds Ca(2+) to move Tm strand away from myosin-binding sites on actin to enable actomyosin cross-bridges required for force generation. The Tn complex has three subunits-Ca(2+)-binding TnC, inhibitory TnI, and Tm-binding TnT. Tm strand is comprised of adjacent Tm molecules that overlap "head-to-tail" along the actin filament. The N-terminus of TnT (e.g., TnT1) binds to the Tm overlap region to form the cTF junction region-the region that connects adjacent regulatory units and confers to cTF internal cooperativity. Numerous studies have predicted interactions among actin, Tm, and TnT1 within the junction region, although a direct structural description of the cTF junction region awaited completion. Here, we report a 3.8 A resolution cryo-EM structure of the native cTF junction region at relaxing (pCa 8) Ca(2+) conditions. We provide novel insights into the "head-to-tail" interactions between adjacent Tm molecules and interactions between the Tm junction with F-actin. We demonstrate how TnT1 stabilizes the Tm overlap region via its interactions with the Tm C- and N-termini and actin. Our data show that TnT1 works as a joint that anchors the Tm overlap region to actin, which stabilizes the relaxed state of the cTF. Our structure provides insight into the molecular basis of cardiac diseases caused by missense mutations in TnT1.

High-resolution cryo-EM structure of the junction region of the native cardiac thin filament in relaxed state.,Risi CM, Belknap B, White HD, Dryden K, Pinto JR, Chase PB, Galkin VE PNAS Nexus. 2022 Dec 16;2(1):pgac298. doi: 10.1093/pnasnexus/pgac298. eCollection , 2023 Jan. PMID:36712934<ref>PMID:36712934</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 8dd0" style="background-color:#fffaf0;"></div>

==See Also==
*[[Tropomyosin 3D structures|Tropomyosin 3D structures]]
*[[Troponin 3D structures|Troponin 3D structures]]
== References ==
<references/>
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</StructureSection>
[[Category: Large Structures]]
[[Category: Sus scrofa]]
[[Category: Galkin VE]]
[[Category: Risi CM]]