Electrostatic Switch Function in the Mechanism of Protein Kinase A I Activation: Results of the Molecular Dynamics Simulation

Figure 2

A-domain conformational transition, events C, D, and E. cAMP, though present in the binding site, is not shown in Figures 2–4. (a) Before events C, D, and E. (b) After events C, D, and E. Side chains of L203, I204, L135, and F136, which form hydrophobic cluster in H-conformation, are shown with grey spheres of van der Waals radii. In (a), L203 side chain is not packed into the pocket formed by β2β3-loop, and the hydrophobic cluster is still stable. In (b), the hydrophobic cluster is destroyed by the L203 packing into the hydrophobic pocket and N3A-motif displacement, B/C-helix is rotated, and Y229 aromatic ring is placed upon L203 side chain, approaching β-subdomain.

(a)

(b)