Band 3 Protein

Band 3 protein, also known as anion exchanger 1 (AE1) or solute carrier family 4 member 1 (SLC4A1)，is a membrane protein encoded by the SLC4A1 gene in humans. It is responsible for mediating the “Chloride-Shift” that includes the exchange of the cellular HCO3^– at a 1:1 ratio with CI^– in plasma. The “Chloride Shift” allows red blood cells to identify metabolically active cells and transport oxygen especially to metabolically active tissues generated carbon dioxide.Band 3 protein, also known as anion exchanger 1 (AE1) or solute carrier family 4 member 1 (SLC4A1)，is a membrane protein encoded by the SLC4A1 gene in humans. It is responsible for mediating the “Chloride-Shift” that includes the exchange of the cellular HCO3^– at a 1:1 ratio with CI^– in plasma. The “Chloride Shift” allows red blood cells to identify metabolically active cells and transport oxygen especially to metabolically active tissues generated carbon dioxide.

Band3 is widely present in vertebrates. There are two specific sites in mammals, each of which is associated with a distinct isoform of the same protein:
•The membrane of red blood cell. The protein isoform is eAE1, which consists of 911 amino acids. eAE1, accounting for 25% of the cell membrane surface, is an essential structural element of the red blood cell membrane.
•The basolateral surface of α-intercalated cells, which are acid-secreting cells, of the kidney’s collecting duct. The protein isoform is kAE1 that is 65 amino acids shorter than eAE1.