title: Reabsorption of neutral amino acids mediated by amino acid transporter LAT2 and TAT1 in the basolateral membrane of proximal tubule.
abstract: In order to understand the renal reabsorption mechanism of neutral amino acids via amino acid transporters, we have isolated human L-type amino acid transporter 2 (hLAT2) and human T-type amino acid transporter 1 (hTAT1) in human, then, we have examined and compared the gene structures, the functional characterizations and the localization in human kidney. Northern blot analysis showed that hLAT2 mRNA was expressed at high levels in the heart, brain, placenta, kidney, spleen, prostate, testis, ovary, lymph node and the fetal liver. The hTAT1 mRNA was detected at high levels in the heart, placenta, liver, skeletal muscle, kidney, pancreas, spleen, thymus and prostate. Immunohistochemical analysis on the human kidney revealed that the hLAT2 and hTAT1 proteins coexist in the basolateral membrane of the renal proximal tubules. The hLAT2 transports all neutral amino acids and hTAT1 transports aromatic amino acids. The basolateral location of the hLAT2 and hTAT1 proteins in the renal proximal tubule as well as the amino acid transport activity of hLAT2 and hTAT1 suggests that these transporters contribute to the renal reabsorption of neutral and aromatic amino acids in the basolateral domain of epithelial proximal tubule cells, respectively. Therefore, LAT2 and TAT1 play essential roles in the reabsorption of neutral amino acids from the epithelial cells to the blood stream in the kidney. Because LAT2 and TAT1 are essential to the efficient absorption of neutral amino acids from the kidney, their defects might be involved in the pathogenesis of disorders caused by a disruption in amino acid absorption such as blue diaper syndrome.
authors.affiliation: Department of Pediatrics, Kwangju Christian Hospital, Gwangju 503-715, Korea.
authors.forename: Sun Young
authors.initials: SY
authors.lastname: Park
authors.forename: Jong-Keun
authors.initials: JK
authors.lastname: Kim
authors.forename: In Jin
authors.initials: IJ
authors.lastname: Kim
authors.forename: Bong Kyu
authors.initials: BK
authors.lastname: Choi
authors.forename: Kyu Yong
authors.initials: KY
authors.lastname: Jung
authors.forename: Seoul
authors.initials: S
authors.lastname: Lee
authors.forename: Kyung Jin
authors.initials: KJ
authors.lastname: Park
authors.forename: Arthit
authors.initials: A
authors.lastname: Chairoungdua
authors.forename: Yoshikatsu
authors.initials: Y
authors.lastname: Kanai
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Endou
authors.forename: Do Kyung
authors.initials: DK
authors.lastname: Kim
mesh_terms: D000042:Absorption; D000595:Amino Acid Sequence; D027182:Amino Acid Transport System y+ / Q000096:biosynthesis* / Q000737:chemistry / Q000235:genetics; D026921:Amino Acid Transport Systems, Neutral / Q000096:biosynthesis* / Q000737:chemistry / Q000235:genetics; D021542:Amino Acids, Neutral / Q000378:metabolism*; D000818:Animals; D001483:Base Sequence; D001692:Biological Transport; D015152:Blotting, Northern; D002874:Chromosome Mapping; D002883:Chromosomes, Human, Pair 14 / Q000235:genetics; D003001:Cloning, Molecular; D027301:Fusion Regulatory Protein 1, Light Chains / Q000096:biosynthesis* / Q000737:chemistry / Q000235:genetics; D006801:Humans; D007150:Immunohistochemistry; D017404:In Situ Hybridization, Fluorescence; D066298:In Vitro Techniques; D007687:Kidney Tubules, Proximal / Q000378:metabolism*; D008969:Molecular Sequence Data; D009865:Oocytes / Q000378:metabolism; D014982:Xenopus laevis
chemical_list: D027182:Amino Acid Transport System y+; D026921:Amino Acid Transport Systems, Neutral; D021542:Amino Acids, Neutral; D027301:Fusion Regulatory Protein 1, Light Chains; C498964:SLC16A10 protein, human; C420646:SLC7A8 protein, human