Final answer:
The Na+/H+ antiporter is the carrier protein present in the membranes of erythrocytes, which helps to regulate the cell's pH by exchanging sodium ions for hydrogen ions.
Step-by-step explanation:
The antiporter present in the membrane of erythrocytes is the Na+/H+ antiporter. This active transport system operates as a secondary active transport mechanism, which uses the energy from the influx of sodium ions to expel hydrogen ions out of the cell, thereby helping to maintain the pH balance within the erythrocyte. Antiporters, like the Na+/H+ antiporter, are a type of carrier proteins that transport two different ions or molecules in opposite directions across a cell membrane.