Here's a schematic diagram of the actin molecule; Holmes & Kabsch (1990) version.Other pictures are provided by the PDB:
As are the x-ray structure co-ordinates.
Below are the figures from Sparrow & Clayton (1995, 'Mutational analysis of the actin molecule and its interaction with actin binding proteins.') which show the sites of mutations which affect either actin:actin, or actin:actin-binding-protein interaction.
Figure 4. (a: actin molecule)
(b: actin:actin)
Figure 5. (a: affect DNaseI)
(b: affect Profilin)
Figure 6. (a: affect myosin)
(b: affect a-actinin/fimbrin)
