Question

The erythrocyte anion exchange protein "ping-pong" transport mechanism involves

A) binding of Cl− on one side of the membrane.
B) binding of bicarbonate ion on one side of the membrane.
C) unidirectional transport of Cl− only out of the cell.
D) two conformational states of the protein.
E) All are involved in the mechanism.

Answer 1

The erythrocyte anion exchange protein involves the binding and exchange of bicarbonate and chloride ions across the membrane, critical for the chloride shift that maintains electrical neutrality during carbon dioxide transport in the blood.

Step-by-step explanation:

The erythrocyte anion exchange protein "ping-pong" transport mechanism indeed involves several steps:

• Binding of bicarbonate ion (HCO3-) on one side of the membrane.
• Exchange of bicarbonate for chloride ions (Cl-) across the erythrocyte membrane.
• Two conformational states of the protein which allow the switch between bicarbonate and chloride binding.

This process is called the chloride shift, which maintains the electrical neutrality of erythrocytes and blood plasma during the transport of carbon dioxide from tissues to the lungs. When carbon dioxide (CO2) enters erythrocytes, it reacts with water to form carbonic acid, which dissociates into bicarbonate ions and hydrogen ions. The excess bicarbonate then leaves the erythrocytes in exchange for chloride ions, a transport mechanism that is crucial in the efficient removal of carbon dioxide from the body.