3 Ontology Annotations
| GO Term | Gene Name |
|---|---|
| GO:0005452 | IPR003024 |
| GO:0006820 | IPR003024 |
| GO:0016020 | IPR003024 |
| Type: | Family | Name: | Sodium bicarbonate cotransporter |
| 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.Na+/HCO3-co-transport proteins are involved in cellular HCO3-absorption and secretion, and also with intracellular pH regulation. They mediate thecoupled movement of Na+and HCO3-across plasma membranes in most of the cell types so far investigated. A single HCO3-is transported together with one to three Na+; this transport mode is therefore often electrogenic. In the kidney, an electrogenic Na+/HCO3-co-transporter is the principal HCO3-transporter of the renal proximal tubule, and is responsible for reabsorption of more than 85% of the filtered load of HCO3-[]. Untilrecently, the molecular nature of these Na+/HCO3-co-transporters had remained undiscovered, as initial attempts to clone them based on presumedhomology to Cl-/HCO3-(anion) exchangers had proved unsuccessful. Instead, an expression cloning strategy was successfully utilised to identify theNa+/HCO3-co-transporter from salamander kidney, an organ previously found to possess electrogenic Na+/HCO3-co-transport activity []. At least 3 mammalian Na+/HCO3-co-transporters have since been cloned, with similar primary sequence lengths and putative membrance topologies. One ofthese has been found to be a kidney-specific isoform [], which isnear-identical (except for a varying N-terminal region) to a more widely-distributed co-transporter cloned from pancreatic tissue []. | Short Name: | Na/HCO3_transpt |
| GO Term | Gene Name |
|---|---|
| GO:0005452 | IPR003024 |
| GO:0006820 | IPR003024 |
| GO:0016020 | IPR003024 |
