Final answer:
The sodium-hydrogen ion antiporter is present in the membrane of erythrocytes and helps maintain the cell's pH.
Step-by-step explanation:
In the membrane of erythrocytes, the antiporter that is present is the sodium-hydrogen ion antiporter. This antiporter uses the energy from the inward flood of sodium ions to move hydrogen ions (H+) out of the cell. The sodium-hydrogen antiporter helps to maintain the pH of the cell's interior.