1fi5
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.
Overview
The N-terminal domain of cardiac troponin I (cTnI) comprising residues, 33-80 and lacking the cardiac-specific amino terminus forms a stable, binary complex with the C-terminal domain of cardiac troponin C (cTnC), comprising residues 81-161. We have utilized heteronuclear, multidimensional NMR to assign the backbone and side-chain resonances of, Ca2+-saturated cTnC(81-161) both free and bound to cTnI(33-80). No, significant differences were observed between secondary structural, elements determined for free and cTnI(33-80)-bound cTnC(81-161). We have, determined solution structures of Ca2+-saturated cTnC(81-161) free and, bound to cTnI(33-80). While the tertiary structure of cTnC(81-161) is, qualitatively similar to that observed free in solution, the binding of, cTnI(33-80) results mainly in an opening of the structure and movement of, the loop region between helices F and G. Together, these movements provide, the binding site for the N-terminal domain of cTnI. The putative binding, site for cTnI(33-80) was determined by mapping amide proton and nitrogen, chemical shift changes, induced by the binding of cTnI(33-80), onto the, C-terminal cTnC structure. The binding interface for cTnI(33-80), as, suggested from chemical shift changes, involves predominantly hydrophobic, interactions located in the expanded hydrophobic pocket. The largest, chemical shift changes were observed in the loop region connecting helices, F and G. Inspection of available TnC sequences reveals that these residues, are highly conserved, suggesting a common binding motif for the, Ca2+/Mg2+-dependent interaction site in the TnC/TnI complex.
About this Structure
1FI5 is a Single protein structure of sequence from Gallus gallus with CA as ligand. This structure superseeds the now removed PDB entry 1GGS. Full crystallographic information is available from OCA.
Reference
Solution structures of the C-terminal domain of cardiac troponin C free and bound to the N-terminal domain of cardiac troponin I., Gasmi-Seabrook GM, Howarth JW, Finley N, Abusamhadneh E, Gaponenko V, Brito RM, Solaro RJ, Rosevear PR, Biochemistry. 1999 Jun 29;38(26):8313-22. PMID:10387077
Page seeded by OCA on Tue Nov 20 14:56:30 2007
