The predominant forms of actin inside a cell are ATP-G-actin and ADP-F actin. What would be the consequence for actin filament assembly/disassembly if a mutation prevented actin's ability to bind ATP

If actin is unable to bind to the ATP molecule, it will not be able to assemble into its two dominant forms.

Explanation:

As shown in the question above, the two predominant forms of actin are ATP-G-actin and ADP-F actin. As we can see, the formation of these two molecules involves the presence of an ATP molecule, in which case, the concentration of actin inside an organism depends totally on the capacity of the actin to be able to bind to an ATP molecule. If there is a mutation that prevents this binding from occurring, actin will not be able to form its two dominant forms, which will harm the presence of actin in the body.