Answer
See the explanation
Work Step by Step
An antiport (also called an exchanger) operates under these rules:
1) Two binding sites: One for solute A, one for solute B.
2) Alternating access: The protein switches conformation to expose binding sites to opposite sides of the membrane.
3) Mutual exclusivity: The protein can switch conformation only when one site is occupied — never when both are occupied or both are empty.
4) Opposite direction transport: Solute A is transported in one direction, while solute B is transported in the opposite direction.
5) Gradient coupling: Movement of solute B down its gradient drives the uphill transport of solute A.
This ensures strict counter-transport, where the exchange of solutes is tightly regulated and energetically favorable.
