1scv
From Proteopedia
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'''NMR STRUCTURE OF THE C TERMINAL DOMAIN OF CARDIAC TROPONIN C BOUND TO THE N TERMINAL DOMAIN OF CARDIAC TROPONIN I''' | '''NMR STRUCTURE OF THE C TERMINAL DOMAIN OF CARDIAC TROPONIN C BOUND TO THE N TERMINAL DOMAIN OF CARDIAC TROPONIN I''' | ||
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[[Category: Howarth, J W.]] | [[Category: Howarth, J W.]] | ||
[[Category: Rosevear, P R.]] | [[Category: Rosevear, P R.]] | ||
| - | [[Category: | + | [[Category: Calcium binding protein]] |
| - | [[Category: | + | [[Category: Cardiac]] |
| - | [[Category: | + | [[Category: Muscle protein]] |
| - | [[Category: | + | [[Category: Troponin c-troponin i interaction]] |
| - | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 08:33:24 2008'' | |
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | + | |
Revision as of 05:33, 3 May 2008
NMR STRUCTURE OF THE C TERMINAL DOMAIN OF CARDIAC TROPONIN C BOUND TO THE N TERMINAL DOMAIN OF CARDIAC TROPONIN I
Overview
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.
About this Structure
1SCV is a Single protein structure of sequence from Gallus gallus. Full crystallographic information is available from OCA.
Reference
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., Finley NL, Howarth JW, Rosevear PR, Biochemistry. 2004 Sep 14;43(36):11371-9. PMID:15350124 Page seeded by OCA on Sat May 3 08:33:24 2008
