Phosphorylation-induced distance change in a cardiac muscle troponin I mutant

The effect of phosphorylation on the distance between the sites located at the C-terminus and N-terminus of the (cTnI) was determined through utilization of fluorescence resonance energy transfer (FRET). Results have shown that both the mean distance and the half-width of the distribution were significantly reduced following PKA-induced phosphorylation of cTnI. It was shown that the phosphorylation induced the folding of the N-terminal extension towards the C-terminal region resulting to altered catalytic activity.