Figure 6. Differences in solvent accessibility between caspase-cleaved non-phosphorylated and autophosphorylated Pak2.

(a) The colored bars illustrate the solvent accessibility changes in the primary sequence. The numbers show the mass (M/Z) of the peptic peptides with a measurable MALDI-TOF signal after H/D exchange. An increase of solvent accessibility following autophosphorylation is shown as the solvent accessibility index. Two fragments (light gray bars), m/z 1476 and 1579, containing Thr⁴⁰² disappeared after phosphorylation. (b) The differences in solvent accessibility are shown on crystal structure of Pak1 (1YHV.PDB). Residues, Trp⁴²⁷ (red) and Gly⁴³⁹ (orange), were statistically coupled to Thr⁴⁰² (blue). Trp⁴²⁷ and Gly⁴³⁹ were in the fragments m/z 1532 and 1828 that had increased solvent accessibility after autophosphorylation.