Document Detail

Influence of a proton gradient on the transport kinetics of the H+/amino acid cotransporter PAT1 in Caco-2 cells.
MedLine Citation:
PMID:  16531028     Owner:  NLM     Status:  MEDLINE    
The recently cloned proton-coupled amino acid transporter 1 (PAT1) not only accepts several amino acids as substrates but also pharmaceutically relevant L-proline or GABA derivatives such as cis-4-hydroxy-L-proline, L-azetidine-2-carboxylic acid (LACA), 3-amino-1-propanesulfonic acid, nipecotic acid, and the antituberculotic agent D-cycloserine. Because human intestine expresses hPAT1 at the brush border membrane, the transporter may serve as a new oral drug delivery route. Using the human intestinal cell line Caco-2, we have investigated the influence of an inwardly directed proton gradient on the kinetic parameters of L-proline uptake. H+ altered only the apparent affinity of L-proline transport and not the maximal transport velocity. Similarly, treatment of the cells with diethylpyrocarbonate (DEPC), known to chemically modify histidyl residues and block their function, affected only the Kt value of L-proline transport. Both increasing pH and DEPC treatment strongly increased the inhibition constants (Ki) of several drugs at hPAT1. It is concluded that H+ stimulates hPAT1 primarily by increasing the substrate affinity with no detectable influence on the maximal transport velocity of the transporter.
Linda Metzner; Matthias Brandsch
Related Documents :
1319998 - Chemical modification of the neutral amino acid transport system l of chinese hamster o...
1567208 - Structural determinants in substrate recognition by proton-amino acid symports in plasm...
1122378 - Transfer of radioactive material between electrically coupled neurons of the leech cent...
2606378 - Peculiarities of amino acid transport in schizosaccharomyces pombe: effects of growth m...
2497728 - Participation of ornithine aminotransferase in the synthesis and catabolism of ornithin...
7675798 - Ascorbate offsets the inhibitory effect of inositol phosphates on iron uptake and trans...
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2006-03-13
Journal Detail:
Title:  European journal of pharmaceutics and biopharmaceutics : official journal of Arbeitsgemeinschaft für Pharmazeutische Verfahrenstechnik e.V     Volume:  63     ISSN:  0939-6411     ISO Abbreviation:  Eur J Pharm Biopharm     Publication Date:  2006 Jul 
Date Detail:
Created Date:  2006-05-30     Completed Date:  2006-10-26     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  9109778     Medline TA:  Eur J Pharm Biopharm     Country:  Netherlands    
Other Details:
Languages:  eng     Pagination:  360-4     Citation Subset:  IM    
Membrane Transport Group, Biozentrum, Martin-Luther-University Halle-Wittenberg, Halle, Germany.
Export Citation:
APA/MLA Format     Download EndNote     Download BibTex
MeSH Terms
Amino Acid Transport Systems / physiology*
Biological Transport
Caco-2 Cells
Hydrogen-Ion Concentration
Proline / metabolism
Symporters / physiology*
Reg. No./Substance:
0/Amino Acid Transport Systems; 0/SLC36A1 protein, human; 0/Symporters; 147-85-3/Proline

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

Previous Document:  In vivo induction of mucosal immune responses by intranasal administration of chitosan microspheres ...
Next Document:  Preparation, characterization, and in vivo anti-ulcer evaluation of pantoprazole-loaded microparticl...