Red cell membrane transport abnormalities

Purpose of review The present review describes the red cell transport abnormalities of proteins of the band 3 macrocomplex. The macrocomplex is involved in red cell gas exchange and recent, findings have furthered our understanding of this process. Recent findings Study of a novel band 3 hereditary spherocytosis variant suggests that expression of mutant band 3 protein can be rescued by wild-type band 3. Other studies show that some mutant band 3 protein can mediate a cation conductance. Recent work suggests both Rh-associated glycoprotein and aquaporin act as gas channels confirming the integrated function of the macrocomplex and the importance of its role in red cell gas transport. Summary The most recent studies on band 3-induced hereditary spherocytosis are reviewed and an explanation for the mild phenotype of heterozygous hereditary spherocytosis is discussed. A number of red cell conditions (hereditary stomatocytosis, south-east Asian ovalocytosis, distal renal tubular acidosis, Rh-null), associated with both stomatocytosis and a cation leak, are described. The evidence that Rh-associated glycoprotein forms a gas channel that transports CO2 and/or NH3 is reviewed and discussed, together with recent studies that show that aquaporin 1 transports both CO2 and O-2.