Group 2 - Cl-/HCO3- exchanger transport Authored: Jassal, B, 2009-06-23 Edited: Jassal, B, 2009-06-23 Pubmed11247665 Pubmed11834742 Pubmed7683425 Pubmed8896562 Pubmed9398842 Reactome Database ID Release 43427666 Reactome, http://www.reactome.org ReactomeREACT_19235 Reviewed: He, L, 2009-08-24 The proteins responsible for the exchange of Cl- with HCO3- are members of the SLC4 (1-3) and SLC26 (3, 4 and 6) transporter families. SLC4 members are discussed in the section "Bicarbonate transporters".<br><br>SLC26A3 (Chloride anion exchanger, Down-regulated in adenoma, DRA) is expressed in the mucosa of the colon and helps mediate electrolyte and fluid absorption (Schweinfest CW et al, 1993). Defects in SLC26A3 cause congenital chloride diarrhea (CLD), a disease characterized by watery stools containing an excess of chloride (Hoeglund P et al, 1996).<br><br>SLC26A4 (Pendrin) is highly expressed in the adult thyroid and its activity is necessary for production of thyroid hormone. (Everett et al, 1997). Mutations in this gene are associated with Pendred syndrome, an autosomal-recessive disease. It is the most common form of syndromic deafness (Everett et al, 1997). Pendred syndrome is also characterized by hypothyroidism.<br><br>SLC26A6 encodes a protein involved in transporting chloride, oxalate, sulfate and bicarbonate (Waldegger S et al, 2001). It is ubiquitously expressed, the highest levels present in kidney and pancreas.