NMR analysis of cardiac troponin C-troponin I complexes: effects of phosphorylation. |
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| Authors: | N Finley M B Abbott E Abusamhadneh V Gaponenko W Dong G Gasmi-Seabrook J W Howarth M Rance R J Solaro H C Cheung P R Rosevear |
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| Affiliation: | Department of Molecular Genetics, Biochemistry, and Microbiology, University of Cincinnati, College of Medicine, OH 45267, USA. |
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| Abstract: | Phosphorylation of the cardiac specific amino-terminus of troponin I has been demonstrated to reduce the Ca2+ affinity of the cardiac troponin C regulatory site. Recombinant N-terminal cardiac troponin I proteins, cardiac troponin I(33-80), cardiac troponin I(1-80), cardiac troponin I(1-80)DD and cardiac troponin I(1-80)pp, phosphorylated by protein kinase A, were used to form stable binary complexes with recombinant cardiac troponin C. Cardiac troponin I(1-80)DD, having phosphorylated Ser residues mutated to Asp, provided a stable mimetic of the phosphorylated state. In all complexes, the N-terminal domain of cardiac troponin I primarily makes contact with the C-terminal domain of cardiac troponin C. The nonphosphorylated cardiac specific amino-terminus, cardiac troponin I(1-80), was found to make additional interactions with the N-terminal domain of cardiac troponin C. |
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