3J4K

Cryo-EM structures of the actin:tropomyosin filament reveal the mechanism for the transition from C- to M-state


Experimental Data Snapshot

  • Method: ELECTRON MICROSCOPY
  • Resolution: 8 Å
  • Aggregation State: FILAMENT 
  • Reconstruction Method: SINGLE PARTICLE 

wwPDB Validation 3D Report Full Report


This is version 1.1 of the entry. See complete history

Literature

Cryo-EM Structures of the Actin:Tropomyosin Filament Reveal the Mechanism for the Transition from C- to M-State.

Sousa, D.R.Stagg, S.M.Stroupe, M.E.

(2013) J.Mol.Biol. 425: 4544-4555

  • DOI: 10.1016/j.jmb.2013.08.020

  • PubMed Abstract: 
  • Tropomyosin (Tm) is a key factor in the molecular mechanisms that regulate the binding of myosin motors to actin filaments (F-Actins) in most eukaryotic cells. This regulation is achieved by the azimuthal repositioning of Tm along the actin (Ac):Tm:t ...

    Tropomyosin (Tm) is a key factor in the molecular mechanisms that regulate the binding of myosin motors to actin filaments (F-Actins) in most eukaryotic cells. This regulation is achieved by the azimuthal repositioning of Tm along the actin (Ac):Tm:troponin (Tn) thin filament to block or expose myosin binding sites on Ac. In striated muscle, including involuntary cardiac muscle, Tm regulates muscle contraction by coupling Ca(2+) binding to Tn with myosin binding to the thin filament. In smooth muscle, the switch is the posttranslational modification of the myosin. Depending on the activation state of Tn and the binding state of myosin, Tm can occupy the blocked, closed, or open position on Ac. Using native cryogenic 3DEM (three-dimensional electron microscopy), we have directly resolved and visualized cardiac and gizzard muscle Tm on filamentous Ac in the position that corresponds to the closed state. From the 8-Å-resolution structure of the reconstituted Ac:Tm filament formed with gizzard-derived Tm, we discuss two possible mechanisms for the transition from closed to open state and describe the role Tm plays in blocking myosin tight binding in the closed-state position.


    Organizational Affiliation

    Department of Biological Science and Institute of Molecular Biophysics, Florida State University, 91 Chieftan Way, Tallahassee, FL 32306, USA; Department of Physiology and Biophysics, Boston University School of Medicine, 72 East Concord Street, Boston, MA 02118-2526, USA.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Actin, alpha skeletal muscle
A, B, C, D, E
375Oryctolagus cuniculusGene Names: ACTA1 (ACTA)
Find proteins for P68135 (Oryctolagus cuniculus)
Go to Gene View: ACTA1
Go to UniProtKB:  P68135
Entity ID: 2
MoleculeChainsSequence LengthOrganismDetails
tropomyosin
F, G
136N/A
Protein Feature View is not available: No corresponding UniProt sequence found.
Small Molecules
Ligands 1 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
ADP
Query on ADP

Download SDF File 
Download CCD File 
A, B, C, D, E
ADENOSINE-5'-DIPHOSPHATE
C10 H15 N5 O10 P2
XTWYTFMLZFPYCI-KQYNXXCUSA-N
 Ligand Interaction
Modified Residues  1 Unique
IDChainsTypeFormula2D DiagramParent
UNK
Query on UNK
F, G
L-PEPTIDE LINKINGC4 H9 N O2

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Experimental Data & Validation

Experimental Data

  • Method: ELECTRON MICROSCOPY
  • Resolution: 8 Å
  • Aggregation State: FILAMENT 
  • Reconstruction Method: SINGLE PARTICLE 

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2013-09-25
    Type: Initial release
  • Version 1.1: 2013-11-13
    Type: Database references