Fig. 7.

Specific packing interactions in the p73–ASPP2 complex. (a) Superposition of the p53 and p73 complexes reveals a significant shift in the position of the n-Src loop, leading to the loss of p73 R268 interaction with ASPP2 D1093 (this side chain was not clearly defined in the electron density). (b) Structural superposition again reveals a shift in the packing of the p73–ASPP2 complex. The L2 loop insertion in p73 induces a subtle change in the position of the H1 helix. Consequently, the loop of the fourth ankyrin repeat in ASPP2 is shifted by ~ 2 Å to avoid steric clashes. Significant sequence changes result in distinct packing interactions in the two complexes.