Figure 7. Phosphorylation at the Serine-Proline Rich Region does not influence changes in conformation following Ca²⁺/calmodulin binding.

CD spectra collected at 20°C for AfRD and AfRD-4SE, AfCaM, and equimolar mixtures of AfCaM:AfRD and AfCaM:AfRD-4SE. Spectra for AfRD-4SE indicate they occupy similar disordered ensembles. Spectra for the AfCaM:AfRD and AfCaN:AfRD-4SE complexes demonstrate that the phospho-mimetic glutamates in AfRD-4SE do not perturb the secondary structure of the bound RD. Also shown is Sum (AfRD+AfCaM), which is the mathematical sum of the AfRD and AfCaM spectra. This is what would be obtained if the AfRD and AfCaM did not interact.