Linked Life Data

2072099

Source:http://linkedlifedata.com/resource/pubmed/id/2072099

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
2
pubmed:dateCreated
1991-8-21
pubmed:abstractText
Isolated rat brain synaptosomes accumulated L-asparagine with a Km value of 348 microM and a Vmax value of 3.7 nmol/mg of protein/min at 28 degrees C. Uptake of L-asparagine was inhibited by the presence of L-glutamine, whereas transport of L-glutamine was blocked by L-asparagine. Alanine, serine, cysteine, threonine, and, in particular, leucine were also inhibitory whereas alpha-(methylamino)isobutyrate, ornithine, lysine, arginine, and glutamate were much less effective blockers. Transport of L-asparagine had a substantial sodium-dependent component, whereas that of the D-stereoisomer was almost unaffected by the presence or absence of the cation. L-Asparagine was accumulated to a maximal gradient, [L-Asn]i/[L-Asn]o, of 20-30, and this value was reduced to 5-6 by withdrawal of sodium or addition of high [KCI]. A plot of log [Na+]o/[Na+]i against the log [L-Asn]i/[L-Asn]o had a slope close to I, which indicates that a single sodium ion is transported inward with each asparagine molecule. It is postulated that uptake of L-asparagine occurs, to a large extent, in cotransport with Na+ and that it utilizes the sodium chemical gradient and the membrane electrical potential as the source of energy. The similarity between the L-asparagine and L-glutamine transport systems and the reciprocal inhibition of influx of the two amino acids suggest that the same mechanism is responsible for glutamine accumulation. This could explain the high [Gln]i maintained by the brain in vivo.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Aug
pubmed:issn
0022-3042
pubmed:author
pubmed:issnType
Print
pubmed:volume
57
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
491-8
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1991
pubmed:articleTitle
Transport of asparagine by rat brain synaptosomes: an approach to evaluate glutamine accumulation.
pubmed:affiliation
Department of Pharmacology, University of Pennsylvania School of Medicine, Philadelphia 19104-6084.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S.