1YV0

Crystal structure of skeletal muscle troponin in the Ca2+-free state


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 7 Å
  • R-Value Free: 0.359 
  • R-Value Work: 0.358 

wwPDB Validation 3D Report Full Report


This is version 1.3 of the entry. See complete history

Literature

Ca2+-regulated structural changes in troponin

Vinogradova, M.V.Stone, D.B.Malanina, G.G.Karatzaferi, C.Cooke, R.Mendelson, R.A.Fletterick, R.J.

(2005) Proc.Natl.Acad.Sci.USA 102: 5038-5043

  • DOI: 10.1073/pnas.0408882102
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 
  • Troponin senses Ca2+ to regulate contraction in striated muscle. Structures of skeletal muscle troponin composed of TnC (the sensor), TnI (the regulator), and TnT (the link to the muscle thin filament) have been determined. The structure of troponin ...

    Troponin senses Ca2+ to regulate contraction in striated muscle. Structures of skeletal muscle troponin composed of TnC (the sensor), TnI (the regulator), and TnT (the link to the muscle thin filament) have been determined. The structure of troponin in the Ca(2+)-activated state features a nearly twofold symmetrical assembly of TnI and TnT subunits penetrated asymmetrically by the dumbbell-shaped TnC subunit. Ca ions are thought to regulate contraction by controlling the presentation to and withdrawal of the TnI inhibitory segment from the thin filament. Here, we show that the rigid central helix of the sensor binds the inhibitory segment of TnI in the Ca(2+)-activated state. Comparison of crystal structures of troponin in the Ca(2+)-activated state at 3.0 angstroms resolution and in the Ca(2+)-free state at 7.0 angstroms resolution shows that the long framework helices of TnI and TnT, presumed to be a Ca(2+)-independent structural domain of troponin are unchanged. Loss of Ca ions causes the rigid central helix of the sensor to collapse and to release the inhibitory segment of TnI. The inhibitory segment of TnI changes conformation from an extended loop in the presence of Ca2+ to a short alpha-helix in its absence. We also show that Anapoe, a detergent molecule, increases the contractile force of muscle fibers and binds specifically, together with the TnI switch helix, in a hydrophobic pocket of TnC upon activation by Ca ions.


    Organizational Affiliation

    Department of Biochemistry and Biophysics, University of California, San Francisco, CA 94143-2240, USA.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Troponin T, fast skeletal muscle isoforms
T
107Gallus gallusMutation(s): 0 
Gene Names: TNNT3
Find proteins for P12620 (Gallus gallus)
Go to Gene View: TNNT3
Go to UniProtKB:  P12620
Entity ID: 2
MoleculeChainsSequence LengthOrganismDetails
Troponin I, fast skeletal muscle
I
137Gallus gallusMutation(s): 2 
Gene Names: TNNI2
Find proteins for P68246 (Gallus gallus)
Go to Gene View: TNNI2
Go to UniProtKB:  P68246
Entity ID: 3
MoleculeChainsSequence LengthOrganismDetails
Troponin C, skeletal muscle
C
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
MG
Query on MG

Download SDF File 
Download CCD File 
C
MAGNESIUM ION
Mg
JLVVSXFLKOJNIY-UHFFFAOYSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 7 Å
  • R-Value Free: 0.359 
  • R-Value Work: 0.358 
  • Space Group: P 43 21 2
Unit Cell:
Length (Å)Angle (°)
a = 134.662α = 90.00
b = 134.662β = 90.00
c = 102.070γ = 90.00
Software Package:
Software NamePurpose
CNSphasing
DENZOdata reduction
SCALEPACKdata scaling
CNSrefinement

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2005-04-12
    Type: Initial release
  • Version 1.1: 2008-04-30
    Type: Version format compliance
  • Version 1.2: 2011-07-13
    Type: Version format compliance
  • Version 1.3: 2018-03-07
    Type: Experimental preparation