title: Characterization of a mouse colonic system B(0+) amino acid transporter related to amino acid absorption in colon.
abstract: Previous experiments have shown that an amino acid transport system B(0+) transporter in cultured colonic epithelial cells mediates amino acid absorption. Here we describe the cloning and functional characterization of a system B(0+) transporter selectively expressed in the colon. Using the combination of an expressed sequence tag database search and RT-PCR approaches, we cloned a mouse colonic amino acid transporter, designated mCATB(0+). Northern blot analysis revealed that mCATB(0+) was selectively expressed in the large intestine. In situ hybridization showed the mCATB(0+) mRNA to be localized in absorptive epithelial cells. When expressed in Xenopus oocytes, mCATB(0+) exhibited a Na(+)-dependent stereoselective uptake and a broad specificity for neutral and cationic amino acids, which is characteristic of amino acid transport system B(0+). In vivo [(3)H]glycine uptake assay demonstrated that a system B(0+)-like transporter protein was expressed on the apical surface of the colonic absorptive cells. Our data suggest that a mouse colonic amino acid transporter mCATB(0+) may absorb amino acids from the intestinal contents in the colon.
authors.affiliation: Department of Anatomy II, Nagoya City University Medical School, 1 Kawasumi, Mizuho-cho, Mizuho-ku, Nagoya 467-8601, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Ugawa
authors.forename: Y
authors.initials: Y
authors.lastname: Sunouchi
authors.forename: T
authors.initials: T
authors.lastname: Ueda
authors.forename: E
authors.initials: E
authors.lastname: Takahashi
authors.forename: Y
authors.initials: Y
authors.lastname: Saishin
authors.forename: S
authors.initials: S
authors.lastname: Shimada
mesh_terms: D000595:Amino Acid Sequence; D026905:Amino Acid Transport Systems; D000596:Amino Acids / Q000378:metabolism*; D000818:Animals; D001483:Base Sequence; D001692:Biological Transport; D002352:Carrier Proteins / Q000235:genetics* / Q000502:physiology*; D002478:Cells, Cultured; D003001:Cloning, Molecular; D003106:Colon / Q000378:metabolism*; D005998:Glycine / Q000378:metabolism; D017403:In Situ Hybridization; D007408:Intestinal Absorption; D051379:Mice; D008969:Molecular Sequence Data; D009865:Oocytes / Q000378:metabolism; D018408:Patch-Clamp Techniques; D050480:Plasma Membrane Neurotransmitter Transport Proteins; D012333:RNA, Messenger / Q000096:biosynthesis; D013379:Substrate Specificity; D014981:Xenopus
chemical_list: D026905:Amino Acid Transport Systems; D000596:Amino Acids; D002352:Carrier Proteins; D050480:Plasma Membrane Neurotransmitter Transport Proteins; D012333:RNA, Messenger; C532353:Slc6A14 protein, mouse; D005998:Glycine