Conformational Changes in Protein Loops and Helices Induced by Post-Translational Phosphorylation
Figure 6
Differences in Conformational Predictions for Phosphorylated CDK2 with and without Cyclin A Bound
The 20 lowest-energy loops are considered for predicting the conformation of residues 152–163 upon in silico phosphorylation of Thr160 (A) in cyclin-bound CDK2 and (B) CDK2 in the absence of cyclin A. In (B), the x-axis represents the deviation of the phosphate from its position in the fully activated CDK2/cyclin A complex; the activation loop and pThr160 are disordered in the crystal structure of phosphorylated CDK2 in the absence of cyclin A. These calculations were performed with a consistent set of parameters that do not bias the results toward well-ordered loop structures. In the absence of cyclin A, the phosphate does not localize to the Arg cluster as in the cyclin bound case, and the 20 lowest-energy structures show considerable diversity in conformation.