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- EMDB-3665: Ca2+-induced Movement of Tropomyosin on Native Cardiac Thin Filam... -
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Open data
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Basic information
Entry | Database: EMDB / ID: EMD-3665 | |||||||||
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Title | Ca2+-induced Movement of Tropomyosin on Native Cardiac Thin Filaments - "Blocked" state | |||||||||
![]() | Native cardiac thin filament in S-blocked state. | |||||||||
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Function / homology | ![]() Striated Muscle Contraction / actin-myosin filament sliding / myosin binding / heart contraction / mesenchyme migration / skeletal muscle thin filament assembly / striated muscle thin filament / skeletal muscle fiber development / stress fiber / sarcomere ...Striated Muscle Contraction / actin-myosin filament sliding / myosin binding / heart contraction / mesenchyme migration / skeletal muscle thin filament assembly / striated muscle thin filament / skeletal muscle fiber development / stress fiber / sarcomere / filopodium / actin filament organization / actin filament / Hydrolases; Acting on acid anhydrides; Acting on acid anhydrides to facilitate cellular and subcellular movement / lamellipodium / cell body / hydrolase activity / positive regulation of gene expression / ATP binding / cytoplasm Similarity search - Function | |||||||||
Biological species | ![]() ![]() ![]() ![]() | |||||||||
Method | helical reconstruction / cryo EM / Resolution: 11.0 Å | |||||||||
![]() | Risi C / Eisner J / Belknap B / Heeley DH / White HD / Schroeder GF / Galkin VE | |||||||||
![]() | ![]() Title: Ca-induced movement of tropomyosin on native cardiac thin filaments revealed by cryoelectron microscopy. Authors: Cristina Risi / Jamie Eisner / Betty Belknap / David H Heeley / Howard D White / Gunnar F Schröder / Vitold E Galkin / ![]() ![]() ![]() Abstract: 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 Ca The current model of ...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 Ca The current model of muscle regulation holds that at relaxing (low-Ca) conditions tropomyosin blocks myosin binding sites on F-actin, whereas at activating (high-Ca) 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 Ca 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 Ca, 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 Ca and lead to a mechanistic model for the regulation of the cardiac TF. | |||||||||
History |
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Structure visualization
Movie |
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Structure viewer | EM map: ![]() ![]() ![]() |
Supplemental images |
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Downloads & links
-EMDB archive
Map data | ![]() | 1.5 MB | ![]() | |
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Header (meta data) | ![]() ![]() | 12.7 KB 12.7 KB | Display Display | ![]() |
Images | ![]() | 77.4 KB | ||
Archive directory | ![]() ![]() | HTTPS FTP |
-Related structure data
Related structure data | ![]() 5nogMC ![]() 3666C ![]() 3667C ![]() 5nojC ![]() 5nolC M: atomic model generated by this map C: citing same article ( |
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Similar structure data |
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Links
EMDB pages | ![]() ![]() |
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Related items in Molecule of the Month |
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Map
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Annotation | Native cardiac thin filament in S-blocked state. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Voxel size | X=Y=Z: 2.1 Å | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Density |
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Symmetry | Space group: 1 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Details | EMDB XML:
CCP4 map header:
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-Supplemental data
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Sample components
-Entire : Native Cardiac Thin Filaments
Entire | Name: Native Cardiac Thin Filaments |
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Components |
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-Supramolecule #1: Native Cardiac Thin Filaments
Supramolecule | Name: Native Cardiac Thin Filaments / type: organelle_or_cellular_component / ID: 1 / Parent: 0 / Macromolecule list: #1-#2 / Details: Sample contains actin, tropomyosin, and troponin. |
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Source (natural) | Organism: ![]() ![]() |
-Macromolecule #1: Cardiac muscle alpha actin 1
Macromolecule | Name: Cardiac muscle alpha actin 1 / type: protein_or_peptide / ID: 1 / Number of copies: 5 / Enantiomer: LEVO |
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Source (natural) | Organism: ![]() ![]() |
Molecular weight | Theoretical: 40.818477 KDa |
Sequence | String: TTALVCDNGS GLVKAGFAGD DAPRAVFPSI VGRPRHQGVM VGMGQKDSYV GDEAQSKRGI LTLKYPIE(HIC)G IITNWD DME KIWHHTFYNE LRVAPEEHPT LLTEAPLNPK ANREKMTQIM FETFNVPAMY VAIQAVLSLY ASGRTTGIVL DSGDGVT HN VPIYEGYALP ...String: TTALVCDNGS GLVKAGFAGD DAPRAVFPSI VGRPRHQGVM VGMGQKDSYV GDEAQSKRGI LTLKYPIE(HIC)G IITNWD DME KIWHHTFYNE LRVAPEEHPT LLTEAPLNPK ANREKMTQIM FETFNVPAMY VAIQAVLSLY ASGRTTGIVL DSGDGVT HN VPIYEGYALP HAIMRLDLAG RDLTDYLMKI LTERGYSFVT TAEREIVRDI KEKLCYVALD FENEMATAAS SSSLEKSY E LPDGQVITIG NERFRCPETL FQPSFIGMES AGIHETTYNS IMKCDIDIRK DLYANNVLSG GTTMYPGIAD RMQKEITAL APSTMKIKII APPERKYSVW IGGSILASLS TFQQMWISKQ EYDEAGPSIV H |
-Macromolecule #2: cardiac alpha tropomyosin
Macromolecule | Name: cardiac alpha tropomyosin / type: protein_or_peptide / ID: 2 / Number of copies: 2 / Enantiomer: LEVO |
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Source (natural) | Organism: ![]() ![]() |
Molecular weight | Theoretical: 11.507176 KDa |
Sequence | String: (UNK)(UNK)(UNK)(UNK)(UNK)(UNK)(UNK)(UNK)(UNK)(UNK) (UNK)(UNK)(UNK)(UNK)(UNK)(UNK) (UNK)(UNK)(UNK) (UNK)(UNK)(UNK)(UNK)(UNK)(UNK)(UNK)(UNK)(UNK)(UNK) (UNK)(UNK)(UNK) (UNK)(UNK)(UNK)(UNK)(UNK) ...String: (UNK)(UNK)(UNK)(UNK)(UNK)(UNK)(UNK)(UNK)(UNK)(UNK) (UNK)(UNK)(UNK)(UNK)(UNK)(UNK) (UNK)(UNK)(UNK) (UNK)(UNK)(UNK)(UNK)(UNK)(UNK)(UNK)(UNK)(UNK)(UNK) (UNK)(UNK)(UNK) (UNK)(UNK)(UNK)(UNK)(UNK)(UNK) (UNK)(UNK)(UNK)(UNK)(UNK)(UNK)(UNK)(UNK)(UNK)(UNK) (UNK)(UNK)(UNK)(UNK)(UNK)(UNK)(UNK)(UNK)(UNK) (UNK)(UNK)(UNK)(UNK)(UNK)(UNK)(UNK) (UNK)(UNK) (UNK)(UNK)(UNK)(UNK)(UNK)(UNK)(UNK)(UNK)(UNK)(UNK) (UNK)(UNK)(UNK)(UNK) (UNK)(UNK)(UNK)(UNK)(UNK) (UNK)(UNK)(UNK)(UNK)(UNK)(UNK)(UNK)(UNK)(UNK)(UNK) (UNK) (UNK)(UNK)(UNK)(UNK)(UNK)(UNK)(UNK)(UNK) (UNK)(UNK)(UNK)(UNK)(UNK)(UNK)(UNK)(UNK) (UNK) (UNK)(UNK)(UNK)(UNK)(UNK)(UNK)(UNK)(UNK)(UNK)(UNK) (UNK)(UNK)(UNK)(UNK)(UNK) (UNK)(UNK)(UNK)(UNK) (UNK)(UNK)(UNK) |
-Macromolecule #3: ADENOSINE-5'-DIPHOSPHATE
Macromolecule | Name: ADENOSINE-5'-DIPHOSPHATE / type: ligand / ID: 3 / Number of copies: 5 / Formula: ADP |
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Molecular weight | Theoretical: 427.201 Da |
Chemical component information | ![]() ChemComp-ADP: |
-Macromolecule #4: MAGNESIUM ION
Macromolecule | Name: MAGNESIUM ION / type: ligand / ID: 4 / Number of copies: 5 / Formula: MG |
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Molecular weight | Theoretical: 24.305 Da |
-Experimental details
-Structure determination
Method | cryo EM |
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![]() | helical reconstruction |
Aggregation state | helical array |
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Sample preparation
Buffer | pH: 7 |
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Vitrification | Cryogen name: ETHANE / Chamber humidity: 95 % / Instrument: FEI VITROBOT MARK IV |
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Electron microscopy
Microscope | FEI TITAN KRIOS |
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Image recording | Film or detector model: FEI FALCON II (4k x 4k) / Average electron dose: 30.0 e/Å2 |
Electron beam | Acceleration voltage: 300 kV / Electron source: ![]() |
Electron optics | Illumination mode: FLOOD BEAM / Imaging mode: BRIGHT FIELD |
Experimental equipment | ![]() Model: Titan Krios / Image courtesy: FEI Company |
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Image processing
Final reconstruction | Applied symmetry - Helical parameters - Δz: 27.7 Å Applied symmetry - Helical parameters - Δ&Phi: 166.8 ° Applied symmetry - Helical parameters - Axial symmetry: C1 (asymmetric) Resolution.type: BY AUTHOR / Resolution: 11.0 Å / Resolution method: FSC 0.5 CUT-OFF / Software - Name: SPIDER / Software - details: IHRSR / Number images used: 3809 |
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CTF correction | Software - Name: CTFFIND (ver. 3) |
Startup model | Type of model: OTHER / Details: solid cylinder |
Final angle assignment | Type: NOT APPLICABLE |
-Atomic model buiding 1
Details | Rigid fitting was done with Chimera and then DireX was used for flexible fitting. |
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Refinement | Space: REAL / Protocol: FLEXIBLE FIT / Target criteria: Cross-correlation coefficient |
Output model | ![]() PDB-5nog: |