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- PDB-8uzy: The structure of the native cardiac thin filament troponin core i... -
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Basic information
Entry | Database: PDB / ID: 8uzy | |||||||||
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Title | The structure of the native cardiac thin filament troponin core in Ca2+-bound partially activated state from the upper strand | |||||||||
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![]() | MOTOR PROTEIN / thin filament / troponin / tropomyosin / cryo-EM / muscle structure | |||||||||
Function / homology | ![]() Striated Muscle Contraction / regulation of muscle filament sliding speed / troponin T binding / cardiac Troponin complex / actin-myosin filament sliding / troponin complex / regulation of muscle contraction / transition between fast and slow fiber / ventricular cardiac muscle tissue morphogenesis / myosin binding ...Striated Muscle Contraction / regulation of muscle filament sliding speed / troponin T binding / cardiac Troponin complex / actin-myosin filament sliding / troponin complex / regulation of muscle contraction / transition between fast and slow fiber / ventricular cardiac muscle tissue morphogenesis / myosin binding / heart contraction / troponin I binding / mesenchyme migration / skeletal muscle contraction / cardiac muscle contraction / sarcomere / actin filament organization / filopodium / actin filament / calcium-dependent protein binding / actin filament binding / actin cytoskeleton / lamellipodium / actin binding / cell body / protein heterodimerization activity / calcium ion binding / positive regulation of gene expression / protein homodimerization activity / identical protein binding / cytoplasm Similarity search - Function | |||||||||
Biological species | ![]() ![]() | |||||||||
Method | ELECTRON MICROSCOPY / single particle reconstruction / cryo EM / Resolution: 5.3 Å | |||||||||
![]() | Galkin, V.E. / Risi, C.M. | |||||||||
Funding support | ![]()
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![]() | ![]() Title: Troponin Structural Dynamics in the Native Cardiac Thin Filament Revealed by Cryo Electron Microscopy. Authors: Cristina M Risi / Betty Belknap / Jennifer Atherton / Isabella Leite Coscarella / Howard D White / P Bryant Chase / Jose R Pinto / Vitold E Galkin / ![]() Abstract: Cardiac muscle contraction occurs due to repetitive interactions between myosin thick and actin thin filaments (TF) regulated by Ca levels, active cross-bridges, and cardiac myosin-binding protein C ...Cardiac muscle contraction occurs due to repetitive interactions between myosin thick and actin thin filaments (TF) regulated by Ca levels, active cross-bridges, and cardiac myosin-binding protein C (cMyBP-C). The cardiac TF (cTF) has two nonequivalent strands, each comprised of actin, tropomyosin (Tm), and troponin (Tn). Tn shifts Tm away from myosin-binding sites on actin at elevated Ca levels to allow formation of force-producing actomyosin cross-bridges. The Tn complex is comprised of three distinct polypeptides - Ca-binding TnC, inhibitory TnI, and Tm-binding TnT. The molecular mechanism of their collective action is unresolved due to lack of comprehensive structural information on Tn region of cTF. C1 domain of cMyBP-C activates cTF in the absence of Ca to the same extent as rigor myosin. Here we used cryo-EM of native cTFs to show that cTF Tn core adopts multiple structural conformations at high and low Ca levels and that the two strands are structurally distinct. At high Ca levels, cTF is not entirely activated by Ca but exists in either partially or fully activated state. Complete dissociation of TnI C-terminus is required for full activation. In presence of cMyBP-C C1 domain, Tn core adopts a fully activated conformation, even in absence of Ca. Our data provide a structural description for the requirement of myosin to fully activate cTFs and explain increased affinity of TnC to Ca in presence of active cross-bridges. We suggest that allosteric coupling between Tn subunits and Tm is required to control actomyosin interactions. | |||||||||
History |
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Structure visualization
Structure viewer | Molecule: ![]() ![]() |
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PDBx/mmCIF format | ![]() | 242.5 KB | Display | ![]() |
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PDB format | ![]() | 186.3 KB | Display | ![]() |
PDBx/mmJSON format | ![]() | Tree view | ![]() | |
Others | ![]() |
-Validation report
Summary document | ![]() | 1.1 MB | Display | ![]() |
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Full document | ![]() | 1.1 MB | Display | |
Data in XML | ![]() | 54.5 KB | Display | |
Data in CIF | ![]() | 79.5 KB | Display | |
Arichive directory | ![]() ![]() | HTTPS FTP |
-Related structure data
Related structure data | ![]() 42847MC ![]() 8uwwC ![]() 8uwxC ![]() 8uwyC ![]() 8uydC ![]() 8uz5C ![]() 8uz6C ![]() 8uzxC ![]() 8v01C ![]() 8v0iC ![]() 8v0kC ![]() 8v0yC M: map data used to model this data C: citing same article ( |
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Similar structure data | Similarity search - Function & homology ![]() |
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Links
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Assembly
Deposited unit | ![]()
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Components
-Protein , 5 types, 7 molecules ABCDEFG
#1: Protein | Mass: 42064.891 Da / Num. of mol.: 2 / Source method: isolated from a natural source / Source: (natural) ![]() ![]() #2: Protein | | Mass: 18433.508 Da / Num. of mol.: 1 / Source method: isolated from a natural source / Source: (natural) ![]() ![]() #3: Protein | | Mass: 24092.680 Da / Num. of mol.: 1 / Source method: isolated from a natural source / Source: (natural) ![]() ![]() #4: Protein | | Mass: 33941.738 Da / Num. of mol.: 1 / Source method: isolated from a natural source / Source: (natural) ![]() ![]() #5: Protein | Mass: 32762.656 Da / Num. of mol.: 2 / Source method: isolated from a natural source / Source: (natural) ![]() ![]() |
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-Non-polymers , 3 types, 7 molecules 




#6: Chemical | #7: Chemical | #8: Chemical | |
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-Details
Has ligand of interest | N |
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-Experimental details
-Experiment
Experiment | Method: ELECTRON MICROSCOPY |
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EM experiment | Aggregation state: FILAMENT / 3D reconstruction method: single particle reconstruction |
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Sample preparation
Component | Name: thin filament troponin core complex / Type: COMPLEX / Entity ID: #1-#5 / Source: NATURAL |
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Molecular weight | Experimental value: NO |
Source (natural) | Organism: ![]() ![]() |
Buffer solution | pH: 7.2 |
Specimen | Embedding applied: NO / Shadowing applied: NO / Staining applied: NO / Vitrification applied: YES / Details: non-helical filament |
Specimen support | Grid material: COPPER / Grid mesh size: 300 divisions/in. / Grid type: EMS Lacey Carbon |
Vitrification | Instrument: FEI VITROBOT MARK IV / Cryogen name: ETHANE / Humidity: 100 % / Chamber temperature: 278 K |
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Electron microscopy imaging
Experimental equipment | ![]() Model: Titan Krios / Image courtesy: FEI Company |
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Microscopy | Model: FEI TITAN KRIOS |
Electron gun | Electron source: ![]() |
Electron lens | Mode: BRIGHT FIELD / Nominal defocus max: 3500 nm / Nominal defocus min: 500 nm |
Specimen holder | Cryogen: NITROGEN / Specimen holder model: FEI TITAN KRIOS AUTOGRID HOLDER |
Image recording | Electron dose: 34 e/Å2 / Film or detector model: GATAN K3 (6k x 4k) / Num. of real images: 24179 |
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Processing
EM software |
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CTF correction | Type: PHASE FLIPPING AND AMPLITUDE CORRECTION | ||||||||||||||||||||||||||||
Particle selection | Num. of particles selected: 8888787 | ||||||||||||||||||||||||||||
3D reconstruction | Resolution: 5.3 Å / Resolution method: FSC 0.143 CUT-OFF / Num. of particles: 91911 / Details: Filtered to 8A / Symmetry type: POINT | ||||||||||||||||||||||||||||
Atomic model building | Protocol: FLEXIBLE FIT / Space: REAL | ||||||||||||||||||||||||||||
Atomic model building |
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