Figure 4: ATP Switch model. Step 1: Cycle initiated by ligand-binding TMDs. Conformational changes transmitted to NBDs enable ATP binding. Step 2: Bound ATP acts as molecular glue in maintaining closed "head-to-tail" NBD dimer, which transmits conformational changes back to TMDs. Resulting in ligand translocation, seen as the power stroke in the transport mechanism. Step 3: ATP hydrolysis enables the conformational changes of NBD dimer dissociation to be transmitted to the TMDs. Step 4: Basal state restored after sequential release of Pi and ADP.
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