PDBsum entry 1sbj

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protein metals links
Contractile protein, structural protein PDB id
Protein chain
81 a.a. *
_MG ×2
* Residue conservation analysis
PDB id:
Name: Contractile protein, structural protein
Title: Nmr structure of the mg2+-loaded c terminal domain of cardiac troponin c bound to the n terminal domain of cardiac troponin i
Structure: Troponin c, slow skeletal and cardiac muscles. Chain: a. Fragment: c-terminal domain (residues 81 - 161). Synonym: tn-c. Engineered: yes
Source: Gallus gallus. Chicken. Organism_taxid: 9031. Gene: ctnc. Expressed in: escherichia coli bl21(de3). Expression_system_taxid: 469008.
NMR struc: 20 models
Authors: N.L.Finley,J.W.Howarth,P.R.Rosevear
Key ref:
N.L.Finley et al. (2004). Structure of the Mg2+-loaded C-lobe of cardiac troponin C bound to the N-domain of cardiac troponin I: comparison with the Ca2+-loaded structure. Biochemistry, 43, 11371-11379. PubMed id: 15350124 DOI: 10.1021/bi049672i
10-Feb-04     Release date:   23-Nov-04    
Go to PROCHECK summary

Protein chain
Pfam   ArchSchema ?
P09860  (TNNC1_CHICK) -  Troponin C, slow skeletal and cardiac muscles
161 a.a.
81 a.a.
Key:    PfamA domain  Secondary structure  CATH domain

 Gene Ontology (GO) functional annotation 
  GO annot!
  Biochemical function     calcium ion binding     1 term  


DOI no: 10.1021/bi049672i Biochemistry 43:11371-11379 (2004)
PubMed id: 15350124  
Structure of the Mg2+-loaded C-lobe of cardiac troponin C bound to the N-domain of cardiac troponin I: comparison with the Ca2+-loaded structure.
N.L.Finley, J.W.Howarth, P.R.Rosevear.
Cardiac troponin C (cTnC) is the Ca(2+)-binding component of the troponin complex and, as such, is the Ca(2+)-dependent switch in muscle contraction. This protein consists of two globular lobes, each containing a pair of EF-hand metal-binding sites, connected by a linker. In the N lobe, Ca(2+)-binding site I is inactive and Ca(2+)-binding site II is primarily responsible for initiation of muscle contraction. The C lobe contains Ca(2+)/Mg(2+)-binding sites III and IV, which bind Mg(2+) with lower affinity and play a structural as well as a secondary role in modulating the Ca(2+) signal. To understand the structural consequences of Ca(2+)/Mg(2+) exchange in the C lobe, we have determined the NMR solution structure of the Mg(2+)-loaded C lobe, cTnC(81-161), in a complex with the N domain of cardiac troponin I, cTnI(33-80), and compared it with a refined Ca(2+)-loaded structure. The overall tertiary structure of the Mg(2+)-loaded C lobe is very similar to that of the refined Ca(2+)-loaded structure as evidenced by the root-mean-square deviation of 0.94 A for all backbone atoms. While metal-dependent conformational changes are minimal, substitution of Mg(2+) for Ca(2+) is characterized by condensation of the C-terminal portion of the metal-binding loops with monodentate Mg(2+) ligation by the conserved Glu at position 12 and partial closure of the cTnI hydrophobic binding cleft around site IV. Thus, conformational plasticity in the Ca(2+)/Mg(2+)-dependent binding loops may represent a mechanism to modulate C-lobe cTnC interactions with the N domain of cTnI.

Literature references that cite this PDB file's key reference

  PubMed id Reference
21312310 W.Ohashi, H.Hirota, and T.Yamazaki (2011).
Solution structure and fluctuation of the Mg(2+)-bound form of calmodulin C-terminal domain.
  Protein Sci, 20, 690-701.
PDB code: 2rrt
21262274 Z.Grabarek (2011).
Insights into modulation of calcium signaling by magnesium in calmodulin, troponin C and related EF-hand proteins.
  Biochim Biophys Acta, 1813, 913-921.  
  20054830 H.Huang, H.Ishida, and H.J.Vogel (2010).
The solution structure of the Mg2+ form of soybean calmodulin isoform 4 reveals unique features of plant calmodulins in resting cells.
  Protein Sci, 19, 475-485.
PDB code: 2ksz
19008222 C.Li, J.Chan, F.Haeseleer, K.Mikoshiba, K.Palczewski, M.Ikura, and J.B.Ames (2009).
Structural insights into Ca2+-dependent regulation of inositol 1,4,5-trisphosphate receptors by CaBP1.
  J Biol Chem, 284, 2472-2481.  
19439414 J.R.Pinto, M.S.Parvatiyar, M.A.Jones, J.Liang, M.J.Ackerman, and J.D.Potter (2009).
A functional and structural study of troponin C mutations related to hypertrophic cardiomyopathy.
  J Biol Chem, 284, 19090-19100.  
18942859 D.S.Pearson, D.R.Swartz, and M.A.Geeves (2008).
Fast pressure jumps can perturb calcium and magnesium binding to troponin C F29W.
  Biochemistry, 47, 12146-12158.  
17056730 M.E.Cantino, and A.Quintanilla (2007).
Cooperative effects of rigor and cycling cross-bridges on calcium binding to troponin C.
  Biophys J, 92, 525-534.  
15711886 M.X.Li, X.Wang, and B.D.Sykes (2004).
Structural based insights into the role of troponin in cardiac muscle pathophysiology.
  J Muscle Res Cell Motil, 25, 559-579.  
15485824 N.L.Finley, and P.R.Rosevear (2004).
Introduction of negative charge mimicking protein kinase C phosphorylation of cardiac troponin I. Effects on cardiac troponin C.
  J Biol Chem, 279, 54833-54840.  
The most recent references are shown first. Citation data come partly from CiteXplore and partly from an automated harvesting procedure. Note that this is likely to be only a partial list as not all journals are covered by either method. However, we are continually building up the citation data so more and more references will be included with time. Where a reference describes a PDB structure, the PDB code is shown on the right.