Document Detail


Basolateral aromatic amino acid transporter TAT1 (Slc16a10) functions as an efflux pathway.
MedLine Citation:
PMID:  16245314     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Basolateral efflux is a necessary step in transepithelial (re)absorption of amino acids from small intestine and kidney proximal tubule. The best characterized basolateral amino acid transporters are y+LAT1-4F2hc and LAT2-4F2hc that function as obligatory exchangers and thus, do not contribute to net amino acid (re)absorption. The aromatic amino acid transporter TAT1 was shown previously to localize basolaterally in rat's small intestine and to mediate the efflux of L-Trp in the absence of exchange substrate, upon expression in Xenopus oocytes. We compared here the amino acid influx and efflux via mouse TAT1 in Xenopus oocytes. The results show that mTAT1 functions as facilitated diffusion pathway for aromatic amino acids and that its properties are symmetrical in terms of selectivity and apparent affinity. We show by real-time RT-PCR that its mRNA is highly expressed in mouse small intestine mucosa, kidney, liver, and skeletal muscle as well as present in all other tested tissues. We show that mTAT1 is not N-glycosylated and that it localizes to the mouse kidney proximal tubule. This expression is characterized by an axial gradient similar to that of the luminal neutral amino acid transporter B0AT1 and shows the same basolateral localization as 4F2hc. mTAT1 also localizes to the basolateral membrane of small intestine enterocytes and to the sinusoidal side of perivenous hepatocytes. In summary, we show that TAT1 is a basolateral epithelial transporter and that it can function as a net efflux pathway for aromatic amino acids. We propose that it, thereby, may supply parallel exchangers with recycling uptake substrates that could drive the efflux of other amino acids.
Authors:
Tamara Ramadan; Simone M R Camargo; Vanessa Summa; Peter Hunziker; Serge Chesnov; Klaas M Pos; Francois Verrey
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Journal of cellular physiology     Volume:  206     ISSN:  0021-9541     ISO Abbreviation:  J. Cell. Physiol.     Publication Date:  2006 Mar 
Date Detail:
Created Date:  2005-12-26     Completed Date:  2006-04-21     Revised Date:  2011-02-07    
Medline Journal Info:
Nlm Unique ID:  0050222     Medline TA:  J Cell Physiol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  771-9     Citation Subset:  IM    
Copyright Information:
Copyright 2005 Wiley-Liss, Inc.
Affiliation:
Institute of Physiology and Centre for Integrative Human Physiology (ZIHP), University of Zürich, Winterthurerstrasse, Zürich, Switzerland.
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MeSH Terms
Descriptor/Qualifier:
Amino Acid Transport Systems, Neutral / chemistry,  metabolism*,  physiology
Amino Acids, Aromatic / metabolism*
Animals
Biological Transport
Fluorescent Antibody Technique
Intestine, Small / metabolism
Kidney Cortex / metabolism
Large Neutral Amino Acid-Transporter 1 / physiology*
Liver / metabolism
Male
Mice
Mice, Inbred C57BL
Oocytes
Phenylalanine / pharmacokinetics
RNA, Messenger / metabolism
Subcellular Fractions
Tissue Distribution
Xenopus laevis
Chemical
Reg. No./Substance:
0/Amino Acid Transport Systems, Neutral; 0/Amino Acids, Aromatic; 0/Large Neutral Amino Acid-Transporter 1; 0/RNA, Messenger; 0/Slc16a10 protein, mouse; 63-91-2/Phenylalanine

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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