2MKP

N domain of cardiac troponin C bound to the switch fragment of fast skeletal troponin I at pH 6


Experimental Data Snapshot

  • Method: SOLUTION NMR
  • Conformers Calculated: 50 
  • Conformers Submitted: 10 
  • Selection Criteria: structures with the least restraint violations 

wwPDB Validation   3D Report Full Report


This is version 1.1 of the entry. See complete history


Literature

Conformation of the critical pH sensitive region of troponin depends upon a single residue in troponin I.

Robertson, I.M.Pineda-Sanabria, S.E.Holmes, P.C.Sykes, B.D.

(2014) Arch Biochem Biophys 552-553: 40-49

  • DOI: 10.1016/j.abb.2013.12.003
  • Primary Citation of Related Structures:  
    2MKP

  • PubMed Abstract: 
  • The calcium sensitivity of cardiac and skeletal muscle is reduced during cytosolic acidosis, and this inhibition is more pronounced in cardiac muscle. Replacing cardiac troponin I with skeletal troponin I reduces the pH sensitivity of cardiac muscle. ...

    The calcium sensitivity of cardiac and skeletal muscle is reduced during cytosolic acidosis, and this inhibition is more pronounced in cardiac muscle. Replacing cardiac troponin I with skeletal troponin I reduces the pH sensitivity of cardiac muscle. This diminished pH sensitivity depends on a single amino acid difference in troponin I: an alanine in cardiac and a histidine in skeletal. Studies suggested that when this histidine is protonated, it forms an electrostatic interaction with glutamate 19 on the surface of cardiac troponin C. Structures of the skeletal and cardiac troponin complexes show very different conformations for the region of troponin I surrounding this residue. In this study, we determined the structure of skeletal troponin I bound to cardiac troponin C. Skeletal troponin I is found to bind to cardiac troponin C with histidine 130 in close proximity to glutamate 19. This conformation is homologous to the crystal structure of the skeletal troponin complex; but different than in the cardiac complex. We show that an A162H variant of cardiac troponin I adopts a conformation similar to the skeletal structure. The implications of these structural differences in the context of cardiac muscle regulation are discussed.


    Organizational Affiliation

    Department of Biochemistry, University of Alberta, 4-19 Medical Sciences Building, Edmonton, Alberta T6G 2H7, Canada. Electronic address: brian.sykes@ualberta.ca.



Macromolecules
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Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
Troponin C, slow skeletal and cardiac musclesC89Homo sapiensMutation(s): 0 
Gene Names: TNNC1TNNC
Find proteins for P63316 (Homo sapiens)
Explore P63316 
Go to UniProtKB:  P63316
NIH Common Fund Data Resources
PHAROS  P63316
Protein Feature View
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  • Reference Sequence
  • Find similar proteins by:  Sequence   |   Structure
Entity ID: 2
MoleculeChainsSequence LengthOrganismDetailsImage
Troponin I, fast skeletal muscleI17Homo sapiensMutation(s): 0 
Gene Names: TNNI2
Find proteins for P48788 (Homo sapiens)
Explore P48788 
Go to UniProtKB:  P48788
NIH Common Fund Data Resources
PHAROS  P48788
Protein Feature View
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  • Reference Sequence
Small Molecules
Ligands 1 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
CA
Query on CA

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

Experimental Data

  • Method: SOLUTION NMR
  • Conformers Calculated: 50 
  • Conformers Submitted: 10 
  • Selection Criteria: structures with the least restraint violations 
  • OLDERADO: 2MKP Olderado

Structure Validation

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Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2014-02-26
    Type: Initial release
  • Version 1.1: 2014-06-18
    Changes: Database references