Activity and Surface Expression of the Intestinal Anion Exchanger Down-Regulated in Adenoma (DRA)

Introduction Down-regulated in adenoma (DRA; SLC26A3) is an intestinal chloride/bicarbonate exchanger that is functionally coupled to NHE3 (Na/H exchanger-isoform 3) in the ileum and proximal colon to mediate electroneutral NaCl absorption. This NaCl absorption is a major regulator of total body volume and electrolyte homeostasis. Knock out of either transporter (DRA or NHE3) causes chronic diarrhea [10,11]. Furthermore, a nonfunctional DRA leads to life-threatening diarrhea (human genetic disorder congenital chloride diarrhea) [2]. NHE3 and several other transport proteins are associated with lipid rafts. These…