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- Carvalho, Eugénia, 1967, et al.
(författare)
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Low cellular IRS 1 gene and protein expression predict insulin resistance and NIDDM.
- 1999
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Ingår i: The FASEB journal : official publication of the Federation of American Societies for Experimental Biology. - 0892-6638 .- 1530-6860. ; 13:15, s. 2173-8
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Tidskriftsartikel (refereegranskat)abstract
- We examined the gene and protein expression of IRS 1 (insulin receptor substrate 1) in adipocytes from two groups of healthy individuals with an increased propensity for non-insulin-dependent diabetes mellitus (NIDDM): those with two first-degree relatives with diabetes and another group with massive obesity. A low expression of IRS 1 (
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| 5. |
- Gustavsson, Johanna, 1956-, et al.
(författare)
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Localization of the insulin receptor in caveolae of adipocyte plasma membrane
- 1999
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Ingår i: The FASEB Journal. - 0892-6638 .- 1530-6860. ; 13:14, s. 1961-1971
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Tidskriftsartikel (refereegranskat)abstract
- The insulin receptor is a transmembrane protein of the plasma membrane, where it recognizes extracellular insulin and transmits signals into the cellular signaling network. We report that insulin receptors are localized and signal in caveolae microdomains of adipocyte plasma membrane. Immunogold electron microscopy and immunofluorescence microscopy show that insulin receptors are restricted to caveolae and are colocalized with caveolin over the plasma membrane. Insulin receptor was enriched in a caveolae-enriched fraction of plasma membrane. By extraction with β-cyclodextrin or destruction with cholesterol oxidase, cholesterol reduction attenuated insulin receptor signaling to protein phosphorylation or glucose transport. Insulin signaling was regained by spontaneous recovery or by exogenous replenishment of cholesterol. β-Cyclodextrin treatment caused a nearly complete annihilation of caveolae invaginations as examined by electron microscopy. This suggests that the receptor is dependent on the caveolae environment for signaling. Insulin stimulation of cells prior to isolation of caveolae or insulin stimulation of the isolated caveolae fraction increased tyrosine phosphorylation of the insulin receptor in caveolae, demonstrating that insulin receptors in caveolae are functional. Our results indicate that insulin receptors are localized to caveolae in the plasma membrane of adipocytes, are signaling in caveolae, and are dependent on caveolae for signaling.
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| 8. |
- Perris, Roberto, et al.
(författare)
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Inhibitory effects of PG-H/aggrecan and PG-M/versican on avian neural crest cell migration
- 1996
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Ingår i: FASEB Journal. - 1530-6860. ; 10:2, s. 293-301
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Tidskriftsartikel (refereegranskat)abstract
- Aggrecans and PG-M/versicans represent two newly defined families of hyaluronan-binding proteoglycans for which the function is still poorly understood. Using the avian neural crest as a model system, we have examined the molecular mechanisms entailed in the cell-proteoglycan interaction during embryonic cell motility. Both the primary cartilage aggrecan of the avian embryo (PG-H/aggrecan) and the largest variant of the avian mesenchymal versican (PG-M/versican VO) failed to support neural crest cell adhesion and migration when topographically immobilized onto the substrate. Conversely, solely the PG-H/aggrecan, and similar aggrecans from other species, counteracted the migration-promoting effect of a number of matrix molecules lacking proteoglycan affinity. This inhibitory effect was not reproduced by the isolated glycosaminoglycan chains, the isolated core protein, the reduced and alkylated macromolecule, or the aggrecan in which the G1 hyaluronan-binding domain had been inactivated with hyaluronan fragments or antibodies. Limited depolymerization of the side chains and preincubation of the PG-H/aggrecan with anti-glycosaminoglycan antibodies differentially reduced the inhibitory activity of the proteoglycan on cell motility. The results demonstrate a diverse inhibitory effect of aggrecans and PG-M/versicans on embryonic cell movement and show that the inhibitory action of aggrecans is independent of substrate binding, is dependent on a G1 domain-mediated association of the intact proteoglycan with cell surface-bound hyaluronan, and is differentially mediated by its glycosaminoglycan side chains.
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| 9. |
- Persson, A, et al.
(författare)
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The purification of membranes by affinity partitioning
- 1995
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Ingår i: FASEB Journal. - 1530-6860. ; 9:13, s. 1304-1310
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Tidskriftsartikel (refereegranskat)abstract
- We describe affinity partitioning as a preparative method for membranes and membraneous structures such as organelles, cells, and viruses. Biospecific affinity partitioning is carried out in aqueous polymer two- phase systems, commonly with polyethylene glycol and dextran as phase polymers, in an environment compatible with membrane structures. Ideally, two-phase conditions are chosen to partition the bulk of membrane material into one phase, while the affinity ligand, conjugated to the second phase polymer, will selectively pull the membranes to be isolated into this phase. Suitable ligands include lectins, antibodies, and receptor-specific agents. Because the method has so far been used successfully in rather few instances, all using high ligand receptor densities in target membranes, the discussion focuses on factors to be considered when developing affinity partitioning conditions using new ligands.
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