2W4U

Isometrically contracting insect asynchronous flight muscle quick frozen after a length step


Experimental Data Snapshot

  • Method: ELECTRON MICROSCOPY
  • Aggregation State: FILAMENT 
  • Reconstruction Method: HELICAL 

wwPDB Validation 3D Report Full Report


This is version 1.3 of the entry. See complete history

Literature

Structural Changes in Isometrically Contracting Insect Flight Muscle Trapped Following a Mechanical Perturbation.

Wu, S.Liu, J.Reedy, M.C.Perz-Edwards, R.J.Tregear, R.T.Winkler, H.Franzini-Armstrong, C.Sasaki, H.Lucaveche, C.Goldman, Y.E.Reedy, M.K.Taylor, K.A.

(2012) Plos One 7: 39422

  • DOI: 10.1371/journal.pone.0039422
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 
  • The application of rapidly applied length steps to actively contracting muscle is a classic method for synchronizing the response of myosin cross-bridges so that the average response of the ensemble can be measured. Alternatively, electron tomography ...

    The application of rapidly applied length steps to actively contracting muscle is a classic method for synchronizing the response of myosin cross-bridges so that the average response of the ensemble can be measured. Alternatively, electron tomography (ET) is a technique that can report the structure of the individual members of the ensemble. We probed the structure of active myosin motors (cross-bridges) by applying 0.5% changes in length (either a stretch or a release) within 2 ms to isometrically contracting insect flight muscle (IFM) fibers followed after 5-6 ms by rapid freezing against a liquid helium cooled copper mirror. ET of freeze-substituted fibers, embedded and thin-sectioned, provides 3-D cross-bridge images, sorted by multivariate data analysis into ~40 classes, distinct in average structure, population size and lattice distribution. Individual actin subunits are resolved facilitating quasi-atomic modeling of each class average to determine its binding strength (weak or strong) to actin. ~98% of strong-binding acto-myosin attachments present after a length perturbation are confined to "target zones" of only two actin subunits located exactly midway between successive troponin complexes along each long-pitch helical repeat of actin. Significant changes in the types, distribution and structure of actin-myosin attachments occurred in a manner consistent with the mechanical transients. Most dramatic is near disappearance, after either length perturbation, of a class of weak-binding cross-bridges, attached within the target zone, that are highly likely to be precursors of strong-binding cross-bridges. These weak-binding cross-bridges were originally observed in isometrically contracting IFM. Their disappearance following a quick stretch or release can be explained by a recent kinetic model for muscle contraction, as behaviour consistent with their identification as precursors of strong-binding cross-bridges. The results provide a detailed model for contraction in IFM that may be applicable to contraction in other types of muscle.


    Related Citations: 
    • Methods for Identifying and Averaging Variable Molecular Conformations in Tomograms of Actively Contracting Insect Flight Muscle.
      Wu, S.,Liu, J.,Reedy, M.C.,Winkler, H.,Reedy, M.K.,Taylor, K.A.
      (2009) J.Struct.Biol. 168: 485


    Organizational Affiliation

    Institute of Molecular Biophysics, Florida State University, Tallahassee, Florida, United States of America.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
TROPONIN C, SKELETAL MUSCLE
0, 3, 6, 9
159Gallus gallusGene Names: TNNC2
Find proteins for P02588 (Gallus gallus)
Go to Gene View: TNNC2
Go to UniProtKB:  P02588
Entity ID: 2
MoleculeChainsSequence LengthOrganismDetails
TROPONIN T, FAST SKELETAL MUSCLE ISOFORMS
1, 4, 7, Y
90Gallus gallusGene Names: TNNT3
Find proteins for P12620 (Gallus gallus)
Go to Gene View: TNNT3
Go to UniProtKB:  P12620
Entity ID: 3
MoleculeChainsSequence LengthOrganismDetails
TROPONIN I, FAST SKELETAL MUSCLE
2, 5, 8, Z
141Gallus gallusGene Names: TNNI2
Find proteins for P68246 (Gallus gallus)
Go to Gene View: TNNI2
Go to UniProtKB:  P68246
Entity ID: 4
MoleculeChainsSequence LengthOrganismDetails
TROPOMYOSIN ALPHA-1 CHAIN
A, B, C, T, U, V, W, X
277Oryctolagus cuniculusGene Names: TPM1 (TPMA)
Find proteins for P58772 (Oryctolagus cuniculus)
Go to Gene View: TPM1
Go to UniProtKB:  P58772
Entity ID: 5
MoleculeChainsSequence LengthOrganismDetails
ACTIN, ALPHA SKELETAL MUSCLE
D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R, S
372Oryctolagus cuniculusGene Names: ACTA1 (ACTA)
Find proteins for P68135 (Oryctolagus cuniculus)
Go to Gene View: ACTA1
Go to UniProtKB:  P68135
Experimental Data & Validation

Experimental Data

  • Method: ELECTRON MICROSCOPY
  • Aggregation State: FILAMENT 
  • Reconstruction Method: HELICAL 

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2010-08-25
    Type: Initial release
  • Version 1.1: 2012-07-18
    Type: Database references
  • Version 1.2: 2012-08-08
    Type: Database references, Version format compliance
  • Version 1.3: 2017-04-19
    Type: Other