Visualizing the elusive open shape of G-actin in solution by SAXS data analysis

- ATP hydrolysis leads to increase in RG of G-actin from 22.3 to 23.7 Ǻ.
- Modeling revealed that shape changes are conserved to ATP binding portion.
- ATP/AMPNP bound G-actin adopts a compact shape.
- ADP bound G-actin is much more open than known crystal structures of the protein alone.
- ADP actin is more like the elusive shape proposed based on hexokinase.