Cardiac troponin I inhibitory peptide: location of interaction sites on troponin C.
Cardiac troponin I(129-149) binds to the calcium saturated cardiac troponin C/troponin I(1-80) complex at two distinct sites. Binding of the first equivalent of troponin I(129-149) was found to primarily affect amide proton chemical shifts in the regulatory domain, while the second equivalent perturbed amide proton chemical shifts within the D/E linker region. Nitrogen-15 transverse relaxation rates showed that binding the first equivalent of inhibitory peptide to the regulatory domain decreased conformational exchange in defunct calcium binding site I and that addition of the second equivalent of inhibitory peptide decreased flexibility in the D/E linker region. No interactions between the inhibitory peptide and the C-domain of cardiac troponin C were detected by these methods demonstrating that the inhibitory peptide cannot displace cTnI(1-80) from the C-domain.
Abbott
M B
MB
Department of Molecular Genetics, Biochemistry, and Microbiology, University of Cincinnati, College of Medicine, 231 Bethesda Ave., Cincinnati, OH 45267, USA.
Dvoretsky
A
A
Gaponenko
V
V
Rosevear
P R
PR
D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002118:Calcium / Q000737:chemistry / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D051379:Mice; D008954:Models, Biological; D008969:Molecular Sequence Data; D009206:Myocardium / Q000737:chemistry*; D010446:Peptide Fragments / Q000737:chemistry* / Q000378:metabolism; D010449:Peptide Mapping; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D019209:Troponin C / Q000737:chemistry* / Q000378:metabolism; D019210:Troponin I / Q000737:chemistry* / Q000378:metabolism
D010446:Peptide Fragments; D019209:Troponin C; D019210:Troponin I; D002118:Calcium