Figure 3. Structural effects of Ca²⁺/CaM binding on smMLCK’s characteristic sequence of conformational states.

(A) Attenuated S${}_0$→S${}_1$ transition in the characteristic force-distance pattern of the smMLCK construct due to conformational changes upon Ca²⁺/CaM binding. This effect is emphasized by a heatmap comparison of several hundred overlaid force-distance curves. Both data sets were collected within one measurement. (B) Structural model interpretation. The S${}_0$→S${}_1$ transition is assigned to a force-induced rearrangement in the kinase domain that correlates with the conformational changes induced by Ca²⁺/CaM binding – the release of the inhibitory pseudosubstrate.

DOI: http://dx.doi.org/10.7554/eLife.26473.023

Figure 3—figure supplement 1. Missing effects by addition of Ca²⁺ without CaM.

The atypical stretching behavior indicating a transition from state S${}_0$ to S${}_1$ is still observable in the presence of Ca²⁺: only in combination with CaM is the barrier not detected in the unfolding pattern.

DOI: http://dx.doi.org/10.7554/eLife.26473.024