Actin and Myosin

ID #2277

What exactly does ATP and ADP have to do with actin?


G-actin monomers can bind ATP. ATP-bound G-actin molecules have high affinities for each other. When the ATP is hydrolyzed to ADP (which, in the case of actin monomers, is not an instantaneous process), the affinity decreases greatly and that ADP-bound G-actin is released. When this happens within a filament, an ADP-bound G-actin that is not at the end of the filament cannot be released. This is why we commonly see ADP-bound G-actins released from the pointed/minus end. It simply takes time for a G-actin monomer to be added to this end, allowing the ADP-actin at the end of the actin filament (in its decreased affinity-state) to be released.

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