3 Ontology Annotations
| GO Term | Gene Name |
|---|---|
| GO:0005452 | IPR002979 |
| GO:0006820 | IPR002979 |
| GO:0016020 | IPR002979 |
| Type: | Family | Name: | Anion exchange protein 3 |
| Description: | Bicarbonate (HCO3-) transport mechanisms are the principal regulators of pH in animal cells. Such transport also plays a vital role in acid-base movements in the stomach, pancreas, intestine, kidney, reproductive organs and the central nervous system. Functional studies have suggested four different HCO3-transport modes. Anion exchanger proteins exchange HCO3-for Cl-in a reversible, electroneutral manner []. Na+/HCO3-co-transport proteins mediate the coupled movement of Na+and HCO3-across plasma membranes, often in an electrogenic manner []. Na-driven Cl-/HCO3-exchange and K+/HCO3-exchange activities have also been detected in certain cell types, although the molecular identities of the proteins responsible remain to be determined.Sequence analysis of the two families of HCO3-transporters that have been cloned to date (the anion exchangers and Na+/HCO3-co-transporters) reveals that they are homologous. This is not entirely unexpected, given that they both transport HCO3-and are inhibited by a class of pharmacological agents called disulphonic stilbenes []. They share around ~25-30% sequence identity, which is distributed along their entire sequence length, and have similar predicted membrane topologies, suggesting they have ~10 transmembrane (TM) domains.Anion exchange proteins participate in pH and cell volume regulation. They are glycosylated, plasma-membrane transport proteins thatexchange hydrogen carbonate (HCO3-) for chloride (Cl-) in a reversible, electroneutral manner [, ]. To date three anion exchanger isoforms havebeen identified (AE1-3), AE1 being the previously-characterised erythrocyteband 3 protein. They share a predicted topology of 12-14 transmembrane (TM) domains, but have differing distribution patterns and cellular localisation.The best characterised isoform, AE1, is known to be the most abundant membrane protein in mature erythrocytes. It has a molecular mass of ~95kDaand consists of two major domains. The N-terminal 390 residues form a water-soluble, highly elongated domain that serves as an attachment site for thebinding of the membrane skeleton and other cytoplasmic proteins. The remainder of the protein is a 55kDa hydrophobic domain that is responsiblefor catalysing anion exchange. The function of the analogous domains of AE2 and AE3 remains to be determined [].AE3 is an anion exchanger that is primarily expressed in the brain and heart. Several tissue-specific variants have been identified, which arisedue to both alternative promoter and exon usage. Two AE3-encoding cDNAs have been isolated from human heart. These clones share long portions of commonsequence but have different 5' ends, therefore encoding distinct N-terminal amino acid sequences. The longer AE3 polypeptide (1232 amino acids) displays~96% amino acid sequence identity to the rat and mouse AE3 'brain isoforms'. The shorter polypeptide (1034 amino acids) corresponds to the rat AE3'cardiac isoform'. Studies of Cl-transport suggest that both isoforms are capable of anion exchange [, ]. | Short Name: | Anion_exchange_3 |
| GO Term | Gene Name |
|---|---|
| GO:0005452 | IPR002979 |
| GO:0006820 | IPR002979 |
| GO:0016020 | IPR002979 |
