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Predicate | Object |
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rdf:type | |
lifeskim:mentions | |
pubmed:issue |
49
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pubmed:dateCreated |
1992-1-17
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pubmed:abstractText |
Kinetic characteristics of glucose transport and glucose phosphorylation were studied in the islet cell line beta TC-1 to explore the roles of these processes in determining the dependence of glucose metabolism and insulin secretion on external glucose. The predominant glucose transporter present was the rat brain/erythrocyte type (Glut1), as determined by RNA and immunoblot analysis. The liver/islet glucose transporter (Glut2) RNA was not detected. The functional parameters of zero-trans glucose entry were Km = 9.5 +/- 2 mM and Vmax = 15.2 +/- 2 nmol min-1 (microL of cell water)-1. Phosphorylation kinetics of two hexokinase activities were characterized in situ. A low-Km (0.036 mM) hexokinase with a Vmax of 0.40 nmol min-1 (microL of cell water)-1 was present along with a high-Km (10 mM) hexokinase, which appeared to conform to a cooperative model with a Hill coefficient of about 1.4 and a Vmax of 0.3 nmol min-1 (microL of cell water)-1. Intracellular glucose at steady state was about 80% of the extracellular glucose from 3 to 15 mM, and transport did not limit metabolism in this range. In this static (nonperifusion) system, 2-3 times more immunoreactive insulin was secreted into the medium at 15 mM glucose than at 3 mM. The dependence of insulin secretion on external glucose roughly paralleled the dependence of glucose metabolism on external glucose. Simulations with a model demonstrated the degree to which changes in transport activity would affect intracellular glucose levels and the rate of the high-Km hexokinase (with the potential to affect insulin release).
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pubmed:grant | |
pubmed:language |
eng
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pubmed:journal | |
pubmed:citationSubset |
IM
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pubmed:chemical | |
pubmed:status |
MEDLINE
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pubmed:month |
Dec
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pubmed:issn |
0006-2960
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pubmed:author | |
pubmed:issnType |
Print
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pubmed:day |
10
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pubmed:volume |
30
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pubmed:owner |
NLM
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pubmed:authorsComplete |
Y
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pubmed:pagination |
11560-6
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pubmed:dateRevised |
2011-11-17
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pubmed:meshHeading |
pubmed-meshheading:1747375-Animals,
pubmed-meshheading:1747375-Biological Transport,
pubmed-meshheading:1747375-Blotting, Northern,
pubmed-meshheading:1747375-Cell Line,
pubmed-meshheading:1747375-Extracellular Space,
pubmed-meshheading:1747375-GTP-Binding Proteins,
pubmed-meshheading:1747375-Glucose,
pubmed-meshheading:1747375-Glycolysis,
pubmed-meshheading:1747375-Insulin,
pubmed-meshheading:1747375-Insulinoma,
pubmed-meshheading:1747375-Intracellular Fluid,
pubmed-meshheading:1747375-Kinetics,
pubmed-meshheading:1747375-Mice,
pubmed-meshheading:1747375-Monosaccharide Transport Proteins,
pubmed-meshheading:1747375-Phosphorylation
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pubmed:year |
1991
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pubmed:articleTitle |
Transport and metabolism of glucose in an insulin-secreting cell line, beta TC-1.
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pubmed:affiliation |
Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee 37232.
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pubmed:publicationType |
Journal Article,
Research Support, U.S. Gov't, P.H.S.,
Research Support, Non-U.S. Gov't
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