title: Effects of troponin I phosphorylation on conformational exchange in the regulatory domain of cardiac troponin C.
abstract: Conformational exchange has been demonstrated within the regulatory domain of calcium-saturated cardiac troponin C when bound to the NH2-terminal domain of cardiac troponin I-(1-80), and cardiac troponin I-(1-80)DD, having serine residues 23 and 24 mutated to aspartate to mimic the phosphorylated form of the protein. Binding of cardiac troponin I-(1-80) decreases conformational exchange for residues 29, 32, and 34. Comparison of average transverse cross correlation rates show that both the NH2- and COOH-terminal domains of cardiac troponin C tumble with similar correlation times when bound to cardiac troponin I-(1-80). In contrast, the NH2- and COOH-terminal domains in free cardiac troponin C and cardiac troponin C bound cardiac troponin I-(1-80)DD tumble independently. These results suggest that the nonphosphorylated cardiac specific NH2 terminus of cardiac troponin I interacts with the NH2-terminal domain of cardiac troponin C.
authors.affiliation: Department of Molecular Genetics, Biochemistry, and Microbiology, University of Cincinnati, College of Medicine, Cincinnati, Ohio 45267, USA.
authors.forename: V
authors.initials: V
authors.lastname: Gaponenko
authors.forename: E
authors.initials: E
authors.lastname: Abusamhadneh
authors.forename: M B
authors.initials: MB
authors.lastname: Abbott
authors.forename: N
authors.initials: N
authors.lastname: Finley
authors.forename: G
authors.initials: G
authors.lastname: Gasmi-Seabrook
authors.forename: R J
authors.initials: RJ
authors.lastname: Solaro
authors.forename: M
authors.initials: M
authors.lastname: Rance
authors.forename: P R
authors.initials: PR
authors.lastname: Rosevear
mesh_terms: D001224:Aspartic Acid / Q000235:genetics; D003198:Computer Simulation; D009154:Mutation; D009206:Myocardium; D019906:Nuclear Magnetic Resonance, Biomolecular; D010766:Phosphorylation; D011485:Protein Binding; D011487:Protein Conformation; D012694:Serine / Q000235:genetics; D012996:Solutions; D019209:Troponin C / Q000737:chemistry / Q000378:metabolism*; D019210:Troponin I / Q000378:metabolism*
chemical_list: D012996:Solutions; D019209:Troponin C; D019210:Troponin I; D001224:Aspartic Acid; D012694:Serine