Band 3

Band 3, also known as anion exchange protein 1 (AE1) or solute carrier family 4 member 1 (SLC4A1), is a protein that in humans is encoded by the SLC4A1 gene. It is an integral membrane protein found primarily in the erythrocyte (red blood cell) membrane and the kidney.

Function

Band 3 is crucial for the exchange of chloride and bicarbonate across the plasma membrane. In erythrocytes, it plays a vital role in maintaining the proper balance of carbon dioxide transport and pH regulation. The protein facilitates the rapid exchange of bicarbonate for chloride ions, a process essential for carbon dioxide transport from tissues to the lungs.

In the kidneys, Band 3 is involved in acid-base homeostasis by reabsorbing bicarbonate from the urine.

Structure

The Band 3 protein is composed of an N-terminal cytoplasmic domain and a C-terminal membrane domain. The cytoplasmic domain interacts with various proteins, including hemoglobin, and plays a role in regulating the protein's function and the shape of the red blood cell. The membrane domain forms the channel through which anions are transported.

Clinical Significance

Mutations in the SLC4A1 gene can lead to several disorders, including hereditary spherocytosis, hereditary elliptocytosis, and Southeast Asian ovalocytosis. These conditions are characterized by abnormalities in red blood cell shape and increased red blood cell destruction (hemolysis), leading to anemia.

Research

Research on Band 3 continues to focus on understanding its role in disease and potential therapeutic targets for conditions involving ion transport disorders.

See also

• Membrane transport protein
• Anion exchange protein
• SLC4A1
• Red blood cell membrane disorders