Experimental Data Snapshot

  • Resolution: 1.78 Å
  • R-Value Work: 0.168 
  • R-Value Observed: 0.168 

wwPDB Validation 3D Report Full Report

This is version 1.2 of the entry. See complete history


Structure of chicken skeletal muscle troponin C at 1.78 A resolution.

Satyshur, K.A.Pyzalska, D.Greaser, M.Rao, S.T.Sundaralingam, M.

(1994) Acta Crystallogr D Biol Crystallogr 50: 40-49

  • DOI: 10.1107/S090744499300798X
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 
  • The structure of chicken skeletal muscle troponin C (TnC) has been refined to an R value of 0.168, using 14 788 reflections, in the resolution range 8.0-1.78 A. Our earlier 2 A resolution structure [Satyshur, Rao, Pyzalska, Drendel, Greaser & Sundara ...

    The structure of chicken skeletal muscle troponin C (TnC) has been refined to an R value of 0.168, using 14 788 reflections, in the resolution range 8.0-1.78 A. Our earlier 2 A resolution structure [Satyshur, Rao, Pyzalska, Drendel, Greaser & Sundaralingam (1988). J. Biol. Chem. 263, 1628-1647] served as the starting model. The refined model includes atoms for all protein residues (1-162), 2 Ca(2+) ions, 169 water molecules and one sulfate ion. The high-resolution refinement shows more clearly the details of the protein and water structure. The side chains Glu63, Cysl01, Arg123, Aspl40 and Asp152 adopt two discretely ordered conformations. The long central helix is only slightly curved/bent (7.9 degrees ) and all the central helix NH.O=C hydrogen bonds are intact. Seven of the nine carbonyl O atoms of the mid segment of this helix, including the D/E linker region, are hydrogen bonded to water molecules which weakens the helix hydrogen bonds. In contrast, in each of the protected upper and lower thirds of the long central helix, only two carbonyl O atoms are hydrogen bonded to water molecules. The hydrogen-bonding patterns displayed by some of the carbonyl O atoms of NT and A helices of the N-terminal domain and the F and H helices of the C-terminal domain, which are on the exposed surface of the protein, are similar. The B helix of the calcium-free site I is kinked, with the local helix axes at either end making an angle of 39 degrees, by two inserted water molecules between N-H and O=C groups, breaking the adjacent helix hydrogen bonds. A sulfate ion from the crystallization buffer is also trapped in the B helix between the guanidinium group of Arg47 and these two inserted water molecules. The C helix of site II is devoid of similar hydration and is probably responsible for the different interhelical angles A/B at site I (134 degrees ) and C/D at site II (149 degrees ). Extensive interhelix hydrogen bonds occur between the side chains of the C and D helices of the 'apo' site II: Gln51-Asp89, Asn52-Asp89, Glu57-Gln85, Glu57-Glu88 and Glu64-Arg84, which apparently are disrupted upon Ca uptake and the resulting rearrangement of the helices expose the side chains, lining the palm of the N-(and C-) terminal domains, for interaction with specific peptide fragment of troponin I (Tnl) during muscle contraction. The dominant crystal packing motif involves a head-to-tail interaction between the N-terminal domain A helix of one molecule and the palm of the C-terminal domain of the 3(2)-related molecule, in a manner similar to that which can be expected for the TnC-TnI complex. Similar interactions may also be responsible for the dimerization of TnC at low pH.

    Related Citations: 
    • Refined Structure of Chicken Skeletal Muscle Troponin C in the Two-Calcium State at 2-Angstroms Resolution
      Satyshur, K.A., Rao, S.T., Pyzalska, D., Drendel, W., Greaser, M., Sundaralingam, M.
      (1988) J Biol Chem 263: 1628
    • Molecular Structure of Troponin C from Chicken Skeletal Muscle at 3-Angstrom Resolution
      Sundaralingam, M., Bergstrom, R., Strasburg, G., Rao, S.T., Roychowdhury, P., Greaser, M., Wang, B.C.
      (1985) Science 227: 945
    • X-Ray Diffraction Studies of Troponin-C Crystals from Rabbit and Chicken Skeletal Muscles
      Strasburg, G.M., Greaser, M.L., Sundaralingam, M.
      (1980) J Biol Chem 255: 3806
    • The Amino Acid Sequence of Troponin C from Chicken Skeletal Muscle
      Wilkinson, J.M.
      (1976) FEBS Lett 70: 254

    Organizational Affiliation

    Crystallography Laboratory, Department of Biochemistry and College of Agriculture and Life Sciences, University of Wisconsin, Madison 53706, USA.

Find similar proteins by:  (by identity cutoff)  |  Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
TROPONIN CA162Gallus gallusMutation(s): 0 
Gene Names: TNNC2
Find proteins for P02588 (Gallus gallus)
Explore P02588 
Go to UniProtKB:  P02588
Protein Feature View
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  • Reference Sequence
Small Molecules
Ligands 2 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
Query on SO4

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O4 S
 Ligand Interaction
Query on CA

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 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Resolution: 1.78 Å
  • R-Value Work: 0.168 
  • R-Value Observed: 0.168 
  • Space Group: P 32 2 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 66.7α = 90
b = 66.7β = 90
c = 60.8γ = 120
Software Package:
Software NamePurpose
X-PLORmodel building

Structure Validation

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Entry History 

Deposition Data

  • Deposited Date: 1993-08-11 
  • Released Date: 1994-01-31 
  • Deposition Author(s): Sundaralingam, M.

Revision History 

  • Version 1.0: 1994-01-31
    Type: Initial release
  • Version 1.1: 2008-03-24
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance