A Membrane-Anchored Cytoplasmic Domain of the Human Insulin Receptor Mediates a Constitutively Elevated Insulin-Independent Uptake of 2-Deoxyglucose*
| Autor: | Eric Clauser, William J. Rutter, David O. Morgan, Richard A. Roth, Leland Ellis |
|---|---|
| Rok vydání: | 1987 |
| Předmět: |
Cytoplasm
Glycosylation medicine.medical_treatment Mutant Deoxyglucose Transfection Cricetulus Transformation Genetic Endocrinology Bacterial Proteins Cricetinae Deoxy Sugars medicine Animals Humans Insulin Tyrosine Molecular Biology biology Chinese hamster ovary cell Cell Membrane Ovary Autophosphorylation General Medicine Protein-Tyrosine Kinases Receptor Insulin Cell biology Insulin receptor Biochemistry biology.protein Phosphorylation Female |
| Zdroj: | Molecular Endocrinology. 1:15-24 |
| ISSN: | 1944-9917 0888-8809 |
| Popis: | Insulin stimulates the autophosphorylation of the beta-subunit of the insulin receptor (IR) on tyrosine residues. Mutations which compromise IR autophosphorylation in vivo result in a decrease of the insulin-activated uptake of 2-deoxyglucose. These results are consistent with previous results which implicate IR autophosphorylation in the generation of the insulin response by cells. To further explore the specificity of the IR tyrosine phosphokinase (TPK) domain in IR function, we have altered the human IR (hIR) cDNA to encode truncated insulin-independent TPKs, which are expressed in chinese hamster ovary (CHO) cells as either membrane-anchored or cytosolic proteins. Both mutant hIRs exhibit TPK activity in vitro, although the cytosolic form is approximately 20 times more active. The carbohydrate moiety of the membrane-anchored form is of the high mannose type, consistent with an intracellular localization for this mutant hIR. The two mutant hIRs mediate very different physiological responses in transfected cells: the membrane-anchored, but not the cytosolic, hIR TPK mediates a constitutively elevated (135% the maximum insulin-stimulated response in CHO cells) insulin-independent uptake of 2-deoxyglucose. These results thus suggest that the hIR TPK is in fact specific for this aspect of IR function and, when membrane-associated, can mediate the insulin-independent uptake of 2-deoxyglucose. Neither of these mutant hIRs appears to transform CHO cells. |
| Databáze: | OpenAIRE |
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