Macromolecule Content

• Total Structure Weight: 10.11 kDa 
• Atom Count: 699 
• Residue Count: 89 
• Unique protein chains: 1

1AP4

REGULATORY DOMAIN OF HUMAN CARDIAC TROPONIN C IN THE CALCIUM-SATURATED STATE, NMR, 40 STRUCTURES

• DOI: 10.2210/pdb1AP4/pdb

• Classification: CALCIUM-BINDING
• Organism(s): Homo sapiens
• Expression System: Escherichia coli
• Mutation(s): No 


• Deposited: 1997-07-24 Released: 1998-07-15 
• Deposition Author(s): Li, M.X., Spyracopoulos, L., Sia, S.K., Gagne, S.M., Chandra, M., Solaro, R.J., Sykes, B.D.

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Experimental Data Snapshot

• Method: SOLUTION NMR
• Conformers Calculated: 43 
• Conformers Submitted: 40 
• Selection Criteria: LEAST RESTRAINT VIOLATION 

Literature

Calcium-induced structural transition in the regulatory domain of human cardiac troponin C.

Spyracopoulos, L., Li, M.X., Sia, S.K., Gagne, S.M., Chandra, M., Solaro, R.J., Sykes, B.D.

(1997) Biochemistry 36: 12138-12146

• PubMed: 9315850 
• DOI: 10.1021/bi971223d
• Structures With Same Primary Citation


• PubMed Abstract: 
  

While calcium binding to troponin C (TnC) triggers the contraction of both skeletal and cardiac muscle, there is clear evidence that different mechanisms may be involved. For example, activation of heart myofilaments occurs with binding to a single regulatory site on TnC, whereas activation of fast skeletal myofilaments occurs with binding to two regulatory sites. The physiological difference between activation of cardiac and skeletal myofilaments is not understood at the molecular level due to a lack of structural details for the response of cardiac TnC to calcium. We determined the solution structures of the apo and calcium-saturated regulatory domain of human cardiac TnC by using multinuclear, multidimensional nuclear magnetic resonance spectroscopy. The structure of apo human cardiac TnC is very similar to that of apo turkey skeletal TnC even though there are critical amino acid substitutions in site I. In contrast to the case with the skeletal protein, the calcium-induced conformational transition in the cardiac regulatory domain does not involve an "opening" of the regulatory domain, and the concomitant exposure of a substantial hydrophobic surface area. This result has important implications with regard to potential unique aspects of the interaction of cardiac TnC with cardiac troponin I and of modification of cardiac myofilament regulation by calcium-sensitizer drugs.

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Organizational Affiliation: 

MRC Group in Protein Structure and Function, Department of Biochemistry, University of Alberta, Edmonton, Canada.

Macromolecules

Entity ID: 1
Molecule	Chains	Sequence Length	Organism	Details
CARDIAC N-TROPONIN C	A	89	Homo sapiens	Mutation(s): 0  Gene Names: TNNC1, TNNC
Find proteins for P63316 (Homo sapiens) Explore P63316  Go to UniProtKB:  P63316
NIH Common Fund Data Resources
PHAROS  P63316 GTEx  ENSG00000114854

Small Molecules

Ligands 1 Unique
ID	Chains	Name / Formula / InChI Key	2D Diagram
CA	A	CALCIUM ION Ca BHPQYMZQTOCNFJ-UHFFFAOYSA-N

Experimental Data & Validation

Experimental Data

• Method: SOLUTION NMR
• Conformers Calculated: 43 
• Conformers Submitted: 40 
• Selection Criteria: LEAST RESTRAINT VIOLATION 
• OLDERADO: 1AP4 Olderado

Structure Validation

Entry History 

Deposition Data

• Deposited Date: 1997-07-24 
• Released Date: 1998-07-15 
Deposition Author(s): Li, M.X., Spyracopoulos, L., Sia, S.K., Gagne, S.M., Chandra, M., Solaro, R.J., Sykes, B.D.

Revision History 

• Version 1.0: 1998-07-15
  Type: Initial release
  
• Version 1.1: 2008-03-24
  Changes: Version format compliance
• Version 1.2: 2011-07-13
  Changes: Version format compliance