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rdf:type | |
lifeskim:mentions | |
pubmed:issue |
15
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pubmed:dateCreated |
1995-5-19
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pubmed:abstractText |
To elucidate the electrical events associated with the movement of amino acids by the neutral and basic amino acid transporter (NBAT)-encoded protein (Yan, N., Mosckovitz, R., Gerber, L.D., Mathew, S., Murty, V.V. V.S., Tate, S.S., and Udenfriend, S. (1994) Proc. Natl. Acad. Sci. USA 91, 7548-7552), we have investigated the membrane potential and current changes associated with the increased transport of amino acids across the cell membrane of NBAT cRNA-injected Xenopus laevis oocytes. Superfusion of 0.05 mM L-phenylalanine, in current-clamped NBAT-injected oocytes, caused a hyperpolarization (8.5 +/- 0.9 mV), but superfusion of L-arginine caused a depolarization (18.3 +/- 1.3 mV). In voltage-clamped (-60 mV) oocytes, superfusion of L-phenylalanine evoked a sodium- and chloride-independent, saturable (Km = 0.34 +/- 0.02 mM, Imax = 31.3 +/- 0.5 nA), outward current. This outward current was reduced in the presence of high external [K] and was barium-sensitive. Outward currents were also evoked by L-leucine, L-glutamine, L-alanine, D-phenylalanine, and L-beta-phenylalanine. Superfusion of L-arginine evoked a saturable (Km = 0.09 +/- 0.02 mM, Imax = -29.2 +/- 1.3 nA) inward current; L-lysine and D-arginine also evoked inward currents. L-Glutamate and beta-alanine failed to evoke any currents. Effluxes of L-[3H]phenylalanine and L-[3H]arginine were trans-stimulated in the presence of either amino acid. Flux-current comparisons indicated amino acid:charge movement stoichiometry of 1:1 for both neutral and cationic amino acids. These findings indicate that the amino acid transport activity(ies) expressed in NBAT cRNA-injected oocytes is electrogenic by a mechanism including the outward movement of a net positive charge (potassium ion or cationic amino acid) in exchange for uptake of a neutral amino acid.
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pubmed:language |
eng
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pubmed:journal | |
pubmed:citationSubset |
IM
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pubmed:chemical |
http://linkedlifedata.com/resource/pubmed/chemical/Amino Acid Transport Systems, Basic,
http://linkedlifedata.com/resource/pubmed/chemical/Amino Acid Transport Systems...,
http://linkedlifedata.com/resource/pubmed/chemical/Amino Acids,
http://linkedlifedata.com/resource/pubmed/chemical/Carrier Proteins,
http://linkedlifedata.com/resource/pubmed/chemical/Cations,
http://linkedlifedata.com/resource/pubmed/chemical/RNA, Complementary,
http://linkedlifedata.com/resource/pubmed/chemical/Sodium,
http://linkedlifedata.com/resource/pubmed/chemical/Sodium Channels
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pubmed:status |
MEDLINE
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pubmed:month |
Apr
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pubmed:issn |
0021-9258
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pubmed:author | |
pubmed:issnType |
Print
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pubmed:day |
14
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pubmed:volume |
270
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pubmed:owner |
NLM
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pubmed:authorsComplete |
Y
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pubmed:pagination |
8482-6
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pubmed:dateRevised |
2006-11-15
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pubmed:meshHeading |
pubmed-meshheading:7721744-Amino Acid Transport Systems, Basic,
pubmed-meshheading:7721744-Amino Acid Transport Systems, Neutral,
pubmed-meshheading:7721744-Amino Acids,
pubmed-meshheading:7721744-Animals,
pubmed-meshheading:7721744-Carrier Proteins,
pubmed-meshheading:7721744-Cations,
pubmed-meshheading:7721744-Membrane Potentials,
pubmed-meshheading:7721744-Microinjections,
pubmed-meshheading:7721744-Oocytes,
pubmed-meshheading:7721744-RNA, Complementary,
pubmed-meshheading:7721744-Sodium,
pubmed-meshheading:7721744-Sodium Channels,
pubmed-meshheading:7721744-Xenopus laevis
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pubmed:year |
1995
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pubmed:articleTitle |
Sodium-independent currents of opposite polarity evoked by neutral and cationic amino acids in neutral and basic amino acid transporter cRNA-injected oocytes.
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pubmed:affiliation |
Department of Anatomy and Physiology, University of Dundee, Scotland.
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pubmed:publicationType |
Journal Article,
Research Support, Non-U.S. Gov't
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