Characterization, cDNA cloning, and functional expression of mouse ileal sodium-dependent bile acid transporter.
Mouse ileal sodium dependent bile acid transporter (ISBT) was characterized using isolated enterocytes. Only enterocytes from the most distal portion showed Na+-dependent [3H]taurocholate uptake. Northern blot analysis using a probe against mouse ISBT revealed the expression of mouse ISBT mRNA to be restricted to the distal ileum. The Km and Vmax for Na+-dependent [3H]taurocholate transport into isolated ileocytes were calculated as 27 microM and 360 pmol/mg protein/min, respectively. Uptake of [3H]taurocholate was inhibited by N-ethylmaleimide. We have cloned ISBT cDNA from mouse ileum. The cDNA included the entire open reading frame coding 348 amino acid protein with seven hydrophobic segments and two N-glycosylation sites. COS-7 cells transfected with the expression vector containing this cDNA expressed Na+-dependent [3H]taurocholate uptake activity with a Km of 34 microM.
Saeki
T
T
Laboratory of Molecular Nutrition, Department of Biological Resource Chemistry, Kyoto Prefectural University, Shimogamo, Sakyo-ku, Kyoto, 606-8522, Japan. tsaeki@dns.kpu.ac.jp
Matoba
K
K
Furukawa
H
H
Kirifuji
K
K
Kanamoto
R
R
Iwami
K
K
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001647:Bile Acids and Salts / Q000378:metabolism*; D001693:Biological Transport, Active; D019556:COS Cells; D002352:Carrier Proteins / Q000235:genetics* / Q000378:metabolism*; D003001:Cloning, Molecular; D017931:DNA Primers / Q000235:genetics; D018076:DNA, Complementary / Q000235:genetics*; D015870:Gene Expression; D006801:Humans; D007082:Ileum / Q000378:metabolism*; D066298:In Vitro Techniques; D007700:Kinetics; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D008969:Molecular Sequence Data; D029363:Organic Anion Transporters, Sodium-Dependent; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D012964:Sodium / Q000378:metabolism*; D027981:Symporters
D001647:Bile Acids and Salts; D002352:Carrier Proteins; D017931:DNA Primers; D018076:DNA, Complementary; D029363:Organic Anion Transporters, Sodium-Dependent; D011994:Recombinant Proteins; D027981:Symporters; C071908:sodium-bile acid cotransporter; D012964:Sodium