1A2X

COMPLEX OF TROPONIN C WITH A 47 RESIDUE (1-47) FRAGMENT OF TROPONIN I


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.30 Å
  • R-Value Free: 0.325 
  • R-Value Work: 0.222 
  • R-Value Observed: 0.222 

wwPDB Validation   3D Report Full Report


This is version 1.2 of the entry. See complete history


Literature

Crystal structure of troponin C in complex with troponin I fragment at 2.3-A resolution.

Vassylyev, D.G.Takeda, S.Wakatsuki, S.Maeda, K.Maeda, Y.

(1998) Proc Natl Acad Sci U S A 95: 4847-4852

  • DOI: 10.1073/pnas.95.9.4847
  • Primary Citation of Related Structures:  
    1A2X

  • PubMed Abstract: 
  • Troponin (Tn), the complex of three subunits (TnC, TnI, and TnT), plays a key role in Ca2+-dependent regulation of muscle contraction. To elucidate the interactions between the Tn subunits and the conformation of TnC in the Tn complex, we have determined the crystal structure of TnC (two Ca2+ bound state) in complex with the N-terminal fragment of TnI (TnI1-47) ...

    Troponin (Tn), the complex of three subunits (TnC, TnI, and TnT), plays a key role in Ca2+-dependent regulation of muscle contraction. To elucidate the interactions between the Tn subunits and the conformation of TnC in the Tn complex, we have determined the crystal structure of TnC (two Ca2+ bound state) in complex with the N-terminal fragment of TnI (TnI1-47). The structure was solved by the single isomorphous replacement method in combination with multiple wavelength anomalous dispersion data. The refinement converged to a crystallographic R factor of 22.2% (Rfree = 32.6%). The central, connecting alpha-helix observed in the structure of uncomplexed TnC (TnCfree) is unwound at the center (residues Ala-87, Lys-88, Gly-89, Lys-90, and Ser-91) and bent by 90 degrees. As a result, TnC in the complex has a compact globular shape with direct interactions between the N- and C-terminal lobes, in contrast to the elongated dumb-bell shaped molecule of uncomplexed TnC. The 31-residue long TnI1-47 alpha-helix stretches on the surface of TnC and stabilizes its compact conformation by multiple contacts with both TnC lobes. The amphiphilic C-end of the TnI1-47 alpha-helix is bound in the hydrophobic pocket of the TnC C-lobe through 38 van der Waals interactions. The results indicate the major difference between Ca2+ receptors integrated with the other proteins (TnC in Tn) and isolated in the cytosol (calmodulin). The TnC/TnI1-47 structure implies a mechanism of how Tn regulates the muscle contraction and suggests a unique alpha-helical regulatory TnI segment, which binds to the N-lobe of TnC in its Ca2+ bound conformation.


    Related Citations: 
    • Production, Crystallization, and Preliminary X-Ray Analysis of Rabbit Skeletal Muscle Troponin Complex Consisting of Troponin C and Fragment (1-47) of Troponin I
      Saijo, Y., Takeda, S., Scherer, A., Kobayashi, T., Maeda, Y., Taniguchi, H., Yao, M., Wakatsuki, S.
      (1997) Protein Sci 6: 916

    Organizational Affiliation

    International Institute for Advanced Research, Central Research Laboratories, Matsushita Electric Industrial Co., Ltd., 3-4 Hikaridai, Seika, Kyoto, 619-02, Japan.



Macromolecules
Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
TROPONIN CA159Oryctolagus cuniculusMutation(s): 0 
Gene Names: TNNC2
UniProt
Find proteins for P02586 (Oryctolagus cuniculus)
Explore P02586 
Go to UniProtKB:  P02586
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP02586
Protein Feature View
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  • Reference Sequence
Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 2
MoleculeChainsSequence LengthOrganismDetailsImage
TROPONIN IB47Oryctolagus cuniculusMutation(s): 0 
Gene Names: TNNI2
UniProt
Find proteins for P02643 (Oryctolagus cuniculus)
Explore P02643 
Go to UniProtKB:  P02643
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP02643
Protein Feature View
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  • Reference Sequence
Small Molecules
Ligands 1 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
CA
Query on CA

Download Ideal Coordinates CCD File 
C [auth A],
D [auth A]
CALCIUM ION
Ca
BHPQYMZQTOCNFJ-UHFFFAOYSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.30 Å
  • R-Value Free: 0.325 
  • R-Value Work: 0.222 
  • R-Value Observed: 0.222 
  • Space Group: P 32 2 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 46.9α = 90
b = 46.9β = 90
c = 152.3γ = 120
Software Package:
Software NamePurpose
X-PLORmodel building
X-PLORrefinement
DENZOdata reduction
SCALEPACKdata scaling
X-PLORphasing

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 1998-07-15
    Type: Initial release
  • Version 1.1: 2008-03-24
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance