Final answer:
Allosteric changes in carrier proteins determine the transitions between different conformations of transporters, specifically regarding the state of the substrate-binding pocket.
Step-by-step explanation:
The transitions between different conformations of transporters, specifically regarding the state of the substrate-binding pocket, are determined by allosteric changes in carrier proteins. These changes occur when a carrier protein binds a solute and undergoes a change in shape. When the solute is released, another allosteric change restores the original conformation of the transport protein. This sequential conformational change allows for the binding and release of substances during transport.