4TNC

REFINED STRUCTURE OF CHICKEN SKELETAL MUSCLE TROPONIN C IN THE TWO-CALCIUM STATE AT 2-ANGSTROMS RESOLUTION


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.00 Å
  • R-Value Observed: 0.172 

wwPDB Validation   3D Report Full Report


This is version 1.3 of the entry. See complete history


Literature

Refined structure of chicken skeletal muscle troponin C in the two-calcium state at 2-A resolution.

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

(1988) J Biol Chem 263: 1628-1647

  • Primary Citation of Related Structures:  
    4TNC

  • PubMed Abstract: 

    The structure of troponin C has been refined at 2A resolution to an R value of 0.172 using a total of 8,100 reflections. Troponin C has an unusual dumbbell shape with only the two C-domain high affinity sites III and IV occupied with metals, while the pair of N-domain low affinity sites I and II are devoid of metals. The coordination of the Ca2+ approaches seven with the last glutamic acid residue in each site forming an asymmetric bidentate ligand. The flanking helices in the metal-bound EF hands are in similar orientation (both 113 degrees) while in the apo sites they are more obtuse (134 and 149 degrees). The EF hands of holo sites III and IV are similar while the apo sites I and II are less similar (rms for backbone atoms, 0.78 and 1.44). The half-loops of the 12-residue holo and apo sites show better agreement than the full loops themselves, suggesting a hinge motion at the midpoint of the loops. The long central helix is stabilized by electrostatic interactions and salt bridges between charged side chains spaced at 3 or 4 residues along the helix. A cluster of water molecules encircle the long helix and hydrogen bond to the backbone carbonyls. At the beginning of the B-helix, a water molecule is interposed at each of two consecutive backbone NH...OC hydrogen bonds. The terminal pair of helices A/D (apo) match with E/H (holo), and the internal pair of helices B/C (apo) match with F/G (holo). Thus, muscle contraction may be triggered by Ca2+ binding to loops I and II which results in a concerted rearrangement of residues in the loops, including the essential Gly at position 6 in each loop. This rearrangement than causes a reorientation of helices B and C along with the BC linker.


  • Organizational Affiliation

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


Macromolecules
Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
TROPONIN C162Gallus gallusMutation(s): 0 
UniProt
Find proteins for P02588 (Gallus gallus)
Explore P02588 
Go to UniProtKB:  P02588
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP02588
Sequence Annotations
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  • Reference Sequence
Small Molecules
Ligands 1 Unique
IDChains Name / Formula / InChI Key2D Diagram3D Interactions
CA
Query on CA

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

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.00 Å
  • R-Value Observed: 0.172 
  • 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
PROLSQrefinement

Structure Validation

View Full Validation Report



Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 1988-07-16
    Type: Initial release
  • Version 1.1: 2008-03-25
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance
  • Version 1.3: 2024-02-28
    Changes: Data collection, Database references, Derived calculations, Other