Crystal structure of the C-terminal region of striated muscle alpha-tropomyosin at 2.7 angstrom resolution

Experimental Data Snapshot

  • Resolution: 2.70 Å
  • R-Value Free: 0.289 
  • R-Value Work: 0.252 
  • R-Value Observed: 0.255 

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The crystal structure of the C-terminal fragment of striated-muscle alpha-tropomyosin reveals a key troponin T recognition site.

Li, Y.Mui, S.Brown, J.H.Strand, J.Reshetnikova, L.Tobacman, L.S.Cohen, C.

(2002) Proc Natl Acad Sci U S A 99: 7378-7383

  • DOI: https://doi.org/10.1073/pnas.102179999
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 

    Contraction in striated and cardiac muscles is regulated by the motions of a Ca(2+)-sensitive tropomyosin/troponin switch. In contrast, troponin is absent in other muscle types and in nonmuscle cells, and actomyosin regulation is myosin-linked. Here we report an unusual crystal structure at 2.7 A of the C-terminal 31 residues of rat striated-muscle alpha-tropomyosin (preceded by a fragment of the GCN4 leucine zipper). The C-terminal 22 residues (263-284) of the structure do not form a two-stranded alpha-helical coiled coil as does the rest of the molecule, but here the alpha-helices splay apart and are stabilized by the formation of a tail-to-tail dimer with a symmetry-related molecule. The site of splaying involves a small group of destabilizing core residues that is present only in striated muscle tropomyosin isoforms. These results reveal a specific recognition site for troponin T and clarify the physical basis for the unique regulatory mechanism of striated muscles.

  • Organizational Affiliation

    Rosenstiel Basic Medical Sciences Research Center, Brandeis University, Waltham, MA 02454-9110, USA.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Fusion Protein of and striated muscle alpha-tropomyosin and the GCN4 leucine zipper
A, B
56Saccharomyces cerevisiaeRattus norvegicus
This entity is chimeric
Mutation(s): 0 
Find proteins for P03069 (Saccharomyces cerevisiae (strain ATCC 204508 / S288c))
Explore P03069 
Go to UniProtKB:  P03069
Find proteins for P04692 (Rattus norvegicus)
Explore P04692 
Go to UniProtKB:  P04692
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupsP03069P04692
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 2.70 Å
  • R-Value Free: 0.289 
  • R-Value Work: 0.252 
  • R-Value Observed: 0.255 
  • Space Group: P 64 2 2
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 137.202α = 90
b = 137.202β = 90
c = 40.071γ = 120
Software Package:
Software NamePurpose
DENZOdata reduction
SCALEPACKdata scaling

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2002-05-29
    Type: Initial release
  • Version 1.1: 2008-04-27
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance
  • Version 1.3: 2017-07-26
    Changes: Refinement description, Source and taxonomy
  • Version 1.4: 2022-12-21
    Changes: Database references