<Tr> <Th> PDB </Th> <Td> RCSB PDB; PDBe; PDBj </Td> </Tr> <Tr> <Th> PDBsum </Th> <Td> structure summary </Td> </Tr> <P> In molecular biology, bicarbonate transporter proteins are proteins which transport bicarbonate . Bicarbonate (HCO) 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 HCO transport modes . Anion exchanger proteins exchange HCO for Cl in a reversible, electroneutral manner . Na / HCO co-transport proteins mediate the coupled movement of Na and HCO across plasma membranes, often in an electrogenic manner . Na driven Cl / HCO exchange and K / HCO exchange activities have also been detected in certain cell types, although the molecular identities of the proteins responsible remain to be determined . </P> <P> Sequence analysis of the two families of HCO transporters that have been cloned to date (the anion exchangers and Na / HCO co-transporters) reveals that they are homologous . This is not entirely unexpected, given that they both transport HCO 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 . </P>

How does bicarbonate gets transported across the cell membrane