1AVS

X-RAY CRYSTALLOGRAPHIC STUDY OF CALCIUM-SATURATED N-TERMINAL DOMAIN OF TROPONIN C

• PDB DOI: https://doi.org/10.2210/pdb1AVS/pdb

• Classification: MUSCLE CONTRACTION
• Organism(s): Gallus gallus
• Expression System: Escherichia coli
• Mutation(s): No 


• Deposited: 1997-09-19 Released: 1997-12-24 
• Deposition Author(s): Strynadka, N.C.J., James, M.N.G.

---

Experimental Data Snapshot

• Method: X-RAY DIFFRACTION
• Resolution: 1.75 Å
• R-Value Free: 
  0.250 (Depositor) 
• R-Value Work: 
  0.214 (Depositor) 
• R-Value Observed: 
  0.220 (Depositor) 

Starting Model: experimental

Literature

Structural details of a calcium-induced molecular switch: X-ray crystallographic analysis of the calcium-saturated N-terminal domain of troponin C at 1.75 A resolution.

Strynadka, N.C., Cherney, M., Sielecki, A.R., Li, M.X., Smillie, L.B., James, M.N.

(1997) J Mol Biol 273: 238-255

• PubMed: 9367759 
• DOI: https://doi.org/10.1006/jmbi.1997.1257
• Primary Citation of Related Structures:  
  1AVS


• PubMed Abstract: 
  

  We have solved and refined the crystal and molecular structures of the calcium-saturated N-terminal domain of troponin C (TnC) to 1.75 A resolution. This has allowed for the first detailed analysis of the calcium binding sites of this molecular switch in the calcium-loaded state. The results provide support for the proposed binding order and qualitatively, for the affinity of calcium in the two regulatory calcium binding sites. Based on a comparison with the high-resolution apo-form of TnC we propose a possible mechanism for the calcium-mediated exposure of a large hydrophobic surface that is central to the initiation of muscle contraction within the cell.

---

Organizational Affiliation: 

Department of Biochemistry, University of Alberta, Edmonton, Canada.

Biological Assembly 1  

Global Symmetry: Asymmetric - C1 
Global Stoichiometry: Monomer - A1 

Biological assembly 1 assigned by authors.

Biological Assembly 2  

Global Symmetry: Asymmetric - C1 
Global Stoichiometry: Monomer - A1 

Biological assembly 2 assigned by authors.

Macromolecule Content

• Total Structure Weight: 20.13 kDa 
• Atom Count: 1,360 
• Modelled Residue Count: 163 
• Deposited Residue Count: 180 
• Unique protein chains: 1

Macromolecules

Entity ID: 1
Molecule	Chains	Sequence Length	Organism	Details	Image
TROPONIN C	A, B	90	Gallus gallus	Mutation(s): 0
UniProt
Find proteins for P02588 (Gallus gallus) Explore P02588  Go to UniProtKB:  P02588

Small Molecules

Ligands 1 Unique
ID	Chains	Name / Formula / InChI Key	2D Diagram
CA	C [auth A], D [auth A], E [auth B], F [auth B]	CALCIUM ION Ca BHPQYMZQTOCNFJ-UHFFFAOYSA-N

Experimental Data & Validation

Experimental Data

• Method: X-RAY DIFFRACTION
• Resolution: 1.75 Å
• R-Value Free:  0.250 (Depositor) 
• R-Value Work:  0.214 (Depositor) 
• R-Value Observed: 0.220 (Depositor) 

Space Group: P 1 2₁ 1

Unit Cell:

Length ( Å )	Angle ( ˚ )
a = 32.12	α = 90
b = 81.58	β = 112.67
c = 39.86	γ = 90

Software Package:

Software Name	Purpose
AMoRE	phasing
MLPHARE	phasing
TNT	refinement
DENZO	data reduction
SCALEPACK	data scaling

Structure Validation

Entry History 

Deposition Data

• Released Date: 1997-12-24 
Deposition Author(s): Strynadka, N.C.J., James, M.N.G.

Revision History  

• Version 1.0: 1997-12-24
  Type: Initial release
  
• Version 1.1: 2008-03-24
  Changes: Version format compliance
• Version 1.2: 2011-07-13
  Changes: Version format compliance
• Version 1.3: 2023-08-02
  Changes: Data collection, Database references, Derived calculations, Refinement description
• Version 1.4: 2024-05-22
  Changes: Data collection