Figure 7. Role of the A2A3 linker in activation and comparison with gelsolin.

(a) Conformation of the A2A3 linker in the inactive structure (grey cartoons) and active model (rainbow-coloured cartoons) of A1–A3. The crystal structure of iA1–A3 was superimposed onto a homology model of the gelsolin-like active conformation through structural alignment of A2. (b,c) Calcium coordination at the type II binding site of domain 2 in the active A1–A3 model (b) and in the crystal structure of actin-bound G1–G3 (PDB 3FFK) (c), highlighting sequence divergence in this region with a more acidic linker in adseverin.