background:
Band 3, also designated AE1, is an erythrocyte membrane glycoprotein that contributes to cell stuctural integrity and mediates exchange of chloride and bicarbonate across the phospholipid bilayer. The diverse functions of the approximately 900 amino acid protein are mediated by two distinct domains. The amino terminal domain, also known as cdb3 for cytoplasmic domain of erthrocyte membrane band 3, acts as an attachment site for the erythrocyte skeleton by binding ankyrin. The carboxy-terminal, membrane-associated domain carries out exchange transport of anions. Degradation of band 3 can generate an aging antigen known as senescent cell antigen, or SCA, which is expressed on old cells and marks them for removal by the immune system. An isoform of band 3, which lacks the first 65 amino acids and does not bind ankryin, is expressed in kidney.
Function:
Band 3 is the major integral glycoprotein of the erythrocyte membrane. Band 3 has two functional domains. Its integral domain mediates a 1:1 exchange of inorganic anions across the membrane, whereas its cytoplasmic domain provides binding sites for cytoskeletal proteins, glycolytic enzymes, and hemoglobin.
Subunit:
A dimer in solution, it spans the membrane asymmetrically and appears to be tetrameric. Interacts (via cytoplasmic N-terminus domain) with ANK1 (via N-terminus ANK repeats).
Subcellular Location:
Membrane; Multi-pass membrane protein.
Tissue Specificity:
Erythrocytes.
Post-translational modifications:
Phosphorylated on Tyr-8 and Tyr-21 most likely by SYK. PP1-resistant phosphorylation that precedes Tyr-359 and Tyr-904 phosphorylation.
Phosphorylated on Tyr-359 and Tyr-904 most likely by LYN. PP1-inhibited phosphorylation that follows Tyr-8 and Tyr-21 phosphorylation.
DISEASE:
Defects in SLC4A1 are the cause of elliptocytosis type 4 (EL4) [MIM:109270]. EL4 is a Rhesus-unlinked form of hereditary elliptocytosis, a genetically heterogeneous, autosomal dominant hematologic disorder. It is characterized by variable hemolytic anemia and elliptical or oval red cell shape.
Defects in SLC4A1 are the cause of spherocytosis type 4 (SPH4) [MIM:612653]; also known as hereditary spherocytosis type 4 (HS4). Spherocytosis is a hematologic disorder leading to chronic hemolytic anemia and characterized by numerous abnormally shaped erythrocytes which are generally spheroidal.
Defects in SLC4A1 are the cause of autosomal dominant distal renal tubular acidosis (AD-dRTA) [MIM:171960]. This disease is characterized by reduced ability to acidify urine, variable hyperchloremic hypokalemic metabolic acidosis, nephrocalcinosis, and nephrolithiasis.
Defects in SLC4A1 are the cause of autosomal recessive distal renal tubular acidosis (AR-dRTA) [MIM:611590].
Similarity:
Belongs to the anion exchanger (TC 2.A.31) family.
Database links:
UniProtKB/Swiss-Prot: P02730.3
Important Note:
This product as supplied is intended for research use only, not for use in human, therapeutic or diagnostic applications.
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