Transmembrane signalling by insulin via an insulin receptor mutated at tyrosines 1158, 1162, and 1163 |
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Authors: | R Rafaeloff B A Maddux A Brunetti P Sbraccia C K Sung R Patel D M Hawley I D Goldfine |
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Institution: | Division of Diabetes and Endocrine Research, Mount Zion Medical Center University of California, San Francisco 94120. |
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Abstract: | In order to study the role of tyrosine autophosphorylation in insulin receptor signalling, we investigated a mutant human insulin receptor whereby the three major tyrosine autophosphorylation sites at positions 1158, 1162, and 1163 in the receptor beta-subunit were mutated to phenylalanines. When these mutant receptors were expressed in HTC rat hepatoma cells, there was no enhanced beta-subunit autophosphorylation and tyrosine kinase activity. In these cells there was enhanced insulin stimulation of 3H]AIB uptake and 3H]thymidine incorporation when compared to wild type HTC cells. The present study suggests therefore that the presence of the major insulin autophosphorylation sites is not a requirement for insulin stimulation of amino acid transport and mitogenesis. |
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