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 Å

wwPDB Validation 3D Report Full Report


This is version 1.2 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


  • 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 th ...

    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.


    Related Citations: 
    • 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
    • The Amino Acid Sequence of Troponin C from Chicken Skeletal Muscle
      Wilkinson, J.M.
      (1976) FEBS Lett. 70: 254
    • 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


    Organizational Affiliation

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




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
TROPONIN C
A
162Gallus gallusMutation(s): 0 
Gene Names: TNNC2
Find proteins for P02588 (Gallus gallus)
Go to Gene View: TNNC2
Go to UniProtKB:  P02588
Small Molecules
Ligands 1 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
CA
Query on CA

Download SDF File 
Download CCD File 
A
CALCIUM ION
Ca
BHPQYMZQTOCNFJ-UHFFFAOYSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2 Å
  • Space Group: P 32 2 1
Unit Cell:
Length (Å)Angle (°)
a = 66.700α = 90.00
b = 66.700β = 90.00
c = 60.800γ = 120.00
Software Package:
Software NamePurpose
PROLSQrefinement

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

  • Deposited Date: 1987-09-28 
  • Released Date: 1988-07-16 
  • Deposition Author(s): Sundaralingam, M.
  • This entry supersedes: 3TNC

Revision History 

  • Version 1.0: 1988-07-16
    Type: Initial release
  • Version 1.1: 2008-03-25
    Type: Version format compliance
  • Version 1.2: 2011-07-13
    Type: Version format compliance