The SLC4 family of HCO3- transporters

Michael F. Romero, Christiaan M. Fulton, Walter F. Boron

Research output: Contribution to journalReview articlepeer-review

354 Scopus citations


The SLC4 family consists of ten genes. All appear to encode integral membrane proteins with very similar hydropathy plots - consistent with the presence of 10-14 transmembrane segments. At least eight SLC4 members encode proteins that transport HCO3- (or a related species, such as CO32-) across the plasma membrane. Functionally, these eight proteins fall into two major groups: three Cl-HCO3 exchangers (AE1-3) and five Na+-coupled HCO3- transporters (NBCe1, NBCe2, NBCn1, NDCBE, NCBE). Two of the Na +-coupled HCO3- transporters (NBCe1, NBCe2) are electrogenic; the other three Na+-coupled HCO3 - transporters and all three AEs are electroneutral. At least NDCBE transports Cl- in addition to Na+ and HCO3 -. Whether NCBE transports Cl- - in addition to Na + and HCO3- - is unsettled. In addition, two other SLC4 members (AE4 and BTR1) do not yet have a firmly established function; on the basis of homology, they fall between the two major groups. A characteristic of many, though not all, SLC4 members is inhibition by 4,4′-diisothiocyanatostilbene-2,2′-disulfonate (DIDS). SLC4 gene products play important roles in the carriage of CO2 by erythrocytes, the absorption or secretion of H+ or HCO3- by several epithelia, as well as the regulation of cell volume and intracellular pH.

Original languageEnglish (US)
Pages (from-to)495-509
Number of pages15
JournalPflugers Archiv European Journal of Physiology
Issue number5
StatePublished - Feb 2004


  • Bicarbonate
  • Boron
  • Carbonate
  • Chloride
  • Cotransporter
  • Exchanger
  • Sodium

ASJC Scopus subject areas

  • Physiology
  • Clinical Biochemistry
  • Physiology (medical)


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