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Predicate | Object |
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rdf:type | |
lifeskim:mentions | |
pubmed:issue |
10
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pubmed:dateCreated |
1985-6-27
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pubmed:abstractText |
A tyrosine group has been identified at, or near, the Na+-binding site of the Na+/glucose and Na+/proline cotransporters of rabbit intestinal brush-borders. Three tyrosine group-specific reagents, n-acetylimidazole, tetranitromethane, and p-nitrobenzene sulfonyl fluoride, were used to evaluate the role of tyrosyl groups in Na+-dependent glucose transport, Na+-dependent phlorizin binding, and the Na+-induced fluorescence quenching of fluorescein isothiocyanate bound to the glucose site of the carrier. All three reagents inhibited glucose transport, phlorizin binding, and fluorescein isothiocyanate quenching by 50-85% with Ki values in the range 7-50 microM. The presence of Na+ during the exposure of membranes to the reagents completely protected against inhibition, the Na+ concentration required to produce 50% protection was 14-36 mM. Fluorescent derivatives of n-acetylimidazole were synthesized to identify the tyrosyl residues on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. A total of five polypeptide bands were labeled with eosin or fluorescein n-acetylimidazole in a Na+-sensitive manner. Two of these bands, previously identified as the glucose (75,000-dalton) and proline (100,000-dalton) binding sites of the glucose and proline carriers, account for 50% of the Na+-sensitive tyrosyl residues. On the basis of these studies, we believe that the Na+/glucose cotransporter contains both the Na+ and glucose active sites on the same polypeptide or that the cotransporter consists of two similar polypeptides, each containing one substrate binding site.
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pubmed:grant | |
pubmed:language |
eng
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pubmed:journal | |
pubmed:citationSubset |
IM
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pubmed:chemical |
http://linkedlifedata.com/resource/pubmed/chemical/Carrier Proteins,
http://linkedlifedata.com/resource/pubmed/chemical/Fluorescein-5-isothiocyanate,
http://linkedlifedata.com/resource/pubmed/chemical/Fluoresceins,
http://linkedlifedata.com/resource/pubmed/chemical/Glucose,
http://linkedlifedata.com/resource/pubmed/chemical/Monosaccharide Transport Proteins,
http://linkedlifedata.com/resource/pubmed/chemical/Phlorhizin,
http://linkedlifedata.com/resource/pubmed/chemical/Sodium,
http://linkedlifedata.com/resource/pubmed/chemical/Tetranitromethane,
http://linkedlifedata.com/resource/pubmed/chemical/Thiocyanates,
http://linkedlifedata.com/resource/pubmed/chemical/Tyrosine
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pubmed:status |
MEDLINE
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pubmed:month |
May
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pubmed:issn |
0021-9258
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pubmed:author | |
pubmed:issnType |
Print
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pubmed:day |
25
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pubmed:volume |
260
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pubmed:owner |
NLM
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pubmed:authorsComplete |
Y
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pubmed:pagination |
6026-31
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pubmed:dateRevised |
2007-11-14
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pubmed:meshHeading |
pubmed-meshheading:3922968-Animals,
pubmed-meshheading:3922968-Binding Sites,
pubmed-meshheading:3922968-Carrier Proteins,
pubmed-meshheading:3922968-Fluorescein-5-isothiocyanate,
pubmed-meshheading:3922968-Fluoresceins,
pubmed-meshheading:3922968-Glucose,
pubmed-meshheading:3922968-Intestine, Small,
pubmed-meshheading:3922968-Kinetics,
pubmed-meshheading:3922968-Microvilli,
pubmed-meshheading:3922968-Monosaccharide Transport Proteins,
pubmed-meshheading:3922968-Phlorhizin,
pubmed-meshheading:3922968-Protein Conformation,
pubmed-meshheading:3922968-Rabbits,
pubmed-meshheading:3922968-Sodium,
pubmed-meshheading:3922968-Tetranitromethane,
pubmed-meshheading:3922968-Thiocyanates,
pubmed-meshheading:3922968-Tyrosine
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pubmed:year |
1985
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pubmed:articleTitle |
Evidence for tyrosyl residues at the Na+ site on the intestinal Na+/glucose cotransporter.
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pubmed:publicationType |
Journal Article,
Comparative Study,
Research Support, U.S. Gov't, P.H.S.
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