Phosphomimetic mutations in the C-terminal basic region of troponin T increases actin filament activity

Abstract

The last 14-16 residues in the C-terminal domain of cardiac and skeletal troponin T (TnT) are essential to achieve full inhibition at low calcium levels (Baxley, Johnson, Pinto and Chalovich, 2017). Those C-terminal residues also prevent Ca2+ from fully activating the regulatory system. Full activation occurs by binding force producing crossbridges to actin. Because the inhibitory region in the C-terminal region of TnT is highly basic, it is possible that phosphorylation of Ser and Thr within that region might also attenuate the limitation on Ca2+ activation.