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Band 3 anion transport protein also known as anion exchanger 1 (AE1) or band 3 or solute carrier family 4 member 1 (SLC4A1) is a protein that in humans is encoded by the SLC4A1 gene. Band 3 anion transport protein is a phylogenetically preserved transport protein responsible for mediating the exchange of chloride (Cl−) for bicarbonate (HCO3−) across a plasma membrane. Functionally similar members of the AE clade are AE2 and AE3. == Function == This is present in the α-intercalated cells of the collecting ducts of the nephron. these are the main acid secreting cells of the kidney. They generate hydrogen ions and bicarbonate ions from carbon dioxide and water - a reaction catalysed by Carbonic anhydrase. The hydrogen ions are pumped into the collecting duct tubule by vacuolar H+ ATPase, the apical proton pump, which thus excretes acid into the urine. kAE1 exchanges bicarbonate for chloride on the basolateral surface, essentially returning bicarbonate to the blood. Here it performs two functions: * Electroneutral chloride and bicarbonate exchange across the plasma membrane on a one-for-one basis.This is crucial for CO2 uptake by the red blood cell and conversion (by hydration catalysed by carbonic anhydrase) into a proton and a bicarbonate ion. The bicarbonate is then extruded (in exchange for a chloride) from the cell by the band 3 molecule. * Physical linkage of the plasma membrane to the underlying membrane skeleton (via binding with ankyrin and protein 4.2). This appears to be to prevent membrane surface loss, rather than being to do with membrane skeleton assembly. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Band 3」の詳細全文を読む スポンサード リンク
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