title: Role of anion exchange transporter PAT1 (SLC26A6) in intestinal absorption of organic anions.
abstract: Mouse PAT1 (putative anion transporter, CEFX, slc26a6), an orthologue of human SLC26A6, was recently identified at the intestinal brush-border membrane and shown to transport organic anions such as formate and oxalate, as well as inorganic ions. In this study, we conducted functional characterization of the uptake of formate by HEK293 cells transfected with PAT1. The uptake of formate by PAT1 was increased in the presence of an outwardly-directed Cl gradient, whereas Na had no effect, and the uptake was independent of pH. The Km of PAT1 for formate was 3.75 mM. Various organic acids exhibited a cis-inhibitory effect on the uptake of formate by PAT1. Furthermore, the uptake was increased by preloading with -lactate, nicotinate, valproate and short-and medium-chain fatty acids, showing a trans-stimulatory effect. Thus, it was suggested that PAT1 transports organic acids as well as inorganic anions, demonstrating that it is involved in the intestinal absorption of anionic organic weak acids in the small intestine.
authors.affiliation: Faculty of Pharmaceutical Sciences, Kanazawa University, Takara-machi 920-0934 Kanazawa, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Nozawa
authors.forename: Shigeki
authors.initials: S
authors.lastname: Sugiura
authors.forename: Yumi
authors.initials: Y
authors.lastname: Hashino
authors.forename: Akira
authors.initials: A
authors.lastname: Tsuji
authors.forename: Ikumi
authors.initials: I
authors.lastname: Tamai
mesh_terms: D026905:Amino Acid Transport Systems / Q000493:pharmacokinetics / Q000502:physiology*; D000818:Animals; D027321:Anion Transport Proteins; D017920:Antiporters / Q000493:pharmacokinetics / Q000502:physiology*; D001693:Biological Transport, Active; D005561:Formates / Q000378:metabolism; D007408:Intestinal Absorption; D051379:Mice; D027361:Organic Anion Transporters / Q000502:physiology*; D010070:Oxalates / Q000378:metabolism; D000076988:Sulfate Transporters; D027981:Symporters
chemical_list: D026905:Amino Acid Transport Systems; D027321:Anion Transport Proteins; D017920:Antiporters; D005561:Formates; D027361:Organic Anion Transporters; D010070:Oxalates; C466903:Slc26a1 protein, mouse; C483904:Slc36a1 protein, mouse; D000076988:Sulfate Transporters; D027981:Symporters; C030544:formic acid