loading...| Preferred Name | Glucose transport | |
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| Definitions |
Cells take up glucose by facilitated diffusion, via glucose transporters (GLUTs) associated with the plasma membrane, a reversible reaction (Joost and Thorens 2001). Four tissue-specific GLUT isoforms are known. Glucose in the cytosol is phosphorylated by tissue-specific kinases to yield glucose 6-phosphate, which cannot cross the plasma membrane because of its negative charge. In the liver, this reaction is catalyzed by glucokinase which has a low affinity for glucose (Km about 10 mM) but is not inhibited by glucose 6-phosphate. In other tissues, this reaction is catalyzed by isoforms of hexokinase. Hexokinases are feedback-inhibited by glucose 6-phosphate and have a high affinity for glucose (Km about 0.1 mM). Liver cells can thus accumulate large amounts of glucose 6-phosphate but only when blood glucose concentrations are high, while most other tissues can take up glucose even when blood glucose concentrations are low but cannot accumulate much intracellular glucose 6-phosphate. These differences are consistent with the view that that the liver functions to buffer blood glucose concentrations, while most other tissues take up glucose to meet immediate metabolic needs.<p>Glucose 6-phosphatase, expressed in liver and kidney, allows glucose 6-phosphate generated by gluconeogenesis (both tissues) and glycogen breakdown (liver) to leave the cell. The absence of glucose 6-phosphatase from other tissues makes glucose uptake by these tissues essentially irreversible, consistent with the view that cells in these tissues take up glucose for local metabolic use. Authored: 2003-02-15 00:00:00 |
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| ID |
http://purl.obolibrary.org/obo/HINO_0015258 |
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| comment |
Cells take up glucose by facilitated diffusion, via glucose transporters (GLUTs) associated with the plasma membrane, a reversible reaction (Joost and Thorens 2001). Four tissue-specific GLUT isoforms are known. Glucose in the cytosol is phosphorylated by tissue-specific kinases to yield glucose 6-phosphate, which cannot cross the plasma membrane because of its negative charge. In the liver, this reaction is catalyzed by glucokinase which has a low affinity for glucose (Km about 10 mM) but is not inhibited by glucose 6-phosphate. In other tissues, this reaction is catalyzed by isoforms of hexokinase. Hexokinases are feedback-inhibited by glucose 6-phosphate and have a high affinity for glucose (Km about 0.1 mM). Liver cells can thus accumulate large amounts of glucose 6-phosphate but only when blood glucose concentrations are high, while most other tissues can take up glucose even when blood glucose concentrations are low but cannot accumulate much intracellular glucose 6-phosphate. These differences are consistent with the view that that the liver functions to buffer blood glucose concentrations, while most other tissues take up glucose to meet immediate metabolic needs. Glucose 6-phosphatase, expressed in liver and kidney, allows glucose 6-phosphate generated by gluconeogenesis (both tissues) and glycogen breakdown (liver) to leave the cell. The absence of glucose 6-phosphatase from other tissues makes glucose uptake by these tissues essentially irreversible, consistent with the view that cells in these tissues take up glucose for local metabolic use. Authored: 2003-02-15 00:00:00 |
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| definition source |
Pubmed11780753 Reactome, http://www.reactome.org |
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| label |
Glucose transport |
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| located_in | ||
| prefixIRI |
HINO:0015258 |
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| prefLabel |
Glucose transport |
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| seeAlso |
GENE ONTOLOGYGO:0015758 Reactome Database ID Release 4370153 ReactomeREACT_212 |
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| subClassOf | ||
| has_part |
http://purl.obolibrary.org/obo/HINO_0019654 http://purl.obolibrary.org/obo/HINO_0019526 http://purl.obolibrary.org/obo/HINO_0015260 http://purl.obolibrary.org/obo/HINO_0019485 http://purl.obolibrary.org/obo/HINO_0019502 http://purl.obolibrary.org/obo/HINO_0019504 http://purl.obolibrary.org/obo/HINO_0019493 |