Characterization of a hybrid receptor formed by dimerization of the insulin receptor-related receptor (IRR) with the insulin receptor (IR): coexpression of cDNAs encoding human IRR and human IR in NIH-3T3 cells.
In many tissues, the insulin receptor-related receptor (IRR) is colocalized with the homologous receptors for insulin and insulin-like growth factor-I (IGF-I). Since a ligand for the IRR has not yet been identified, it has been proposed previously that IRR may be activated and transduce its signal via formation of hybrids with the insulin and IGF-I receptors. To test this hypothesis, we have coexpressed the human IRR and the human insulin receptor (IR) in NIH-3T3 cells. Although IRR/IR hybrid receptors were detected in these cells by using immunoprecipitation techniques, only a small proportion of each receptor was assembled into hybrids. While insulin was capable of stimulating insulin receptors autophosphorylation in these cells, there was no detectable increase in the total phosphotyrosine content of IRR. We conclude that the IRR/IR hybrid receptor does not play a major role in IRR signal transduction in response to insulin in NIH-3T3-hIRR/hIR cells.
Diabetes Branch, National Institute of Diabetes and Digestive and Kidney Disease, National Institutes of Health, Bethesda, Maryland 20892-1770, USA.
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D016475:3T3 Cells; D000818:Animals; D006801:Humans; D007328:Insulin / Q000378:metabolism; D046911:Macromolecular Substances; D051379:Mice; D010766:Phosphorylation; D019000:Phosphotyrosine / Q000378:metabolism; D011485:Protein Binding; D011972:Receptor, Insulin / Q000737:chemistry* / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry
D007328:Insulin; D046911:Macromolecular Substances; D011994:Recombinant Proteins; D019000:Phosphotyrosine; D011972:Receptor, Insulin; C066542:insulin receptor-related receptor