Figure 4

Scheme describing the different conformational states of Src.
The free protein is in slow exchange between two conformations: hinge-open (top) and closed (bottom). This equilibrium remains even after the phosphorylation of the activation loop (represented by a yellow sphere). Phosphorylation causes a conformational change leading to the opening of the A-loop. Binding of ATP (or ADP) leads to a final conformational switch towards the minor form observed in solution.