NMR analysis of cardiac troponin C-troponin I complexes: effects of phosphorylation.
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.
Finley
N
N
Department of Molecular Genetics, Biochemistry, and Microbiology, University of Cincinnati, College of Medicine, OH 45267, USA.
Abbott
M B
MB
Abusamhadneh
E
E
Gaponenko
V
V
Dong
W
W
Gasmi-Seabrook
G
G
Howarth
J W
JW
Rance
M
M
Solaro
R J
RJ
Cheung
H C
HC
Rosevear
P R
PR
D000595:Amino Acid Sequence; D008969:Molecular Sequence Data; D009206:Myocardium / Q000737:chemistry*; D019906:Nuclear Magnetic Resonance, Biomolecular; D010750:Phosphoproteins / Q000737:chemistry* / Q000378:metabolism; D010766:Phosphorylation; D011485:Protein Binding; D017433:Protein Structure, Secondary; D019209:Troponin C / Q000737:chemistry* / Q000378:metabolism; D019210:Troponin I / Q000737:chemistry* / Q000378:metabolism
D010750:Phosphoproteins; D019209:Troponin C; D019210:Troponin I