Insulin receptors in rat brain: insulin stimulates phosphorylation of its receptor beta-subunit |
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Authors: | S Gammeltoft A Kowalski M Fehlmann E van Obberghen |
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Institution: | 1. Department of Clinical Chemistry CL 3011, Rigshospitalet, University Hospital, Blegdamsvej 9, DK 2100 Copenhagen, Denmark;2. Institut National de la Santé et de la Recherche Médicale (INSERM U145), Faculté de Médecine, Avenue de Vallombrose, 06034 Nice Cédex, France |
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Abstract: | In rat brain cortex synaptosomes insulin stimulated the phosphorylation of its own receptor beta-subunit (94 kDa) as identified by immunoprecipitation with anti-insulin or anti-receptor antiserum. The receptor alpha-subunit (115 kDa) was characterized by specific labeling with 125I-labeled photoreactive insulin. These observations indicate that: (i) insulin receptors in brain are composed of alpha-subunits which bind insulin, and beta-subunits, the phosphorylation of which can be stimulated by insulin; (ii) the size of alpha-subunits in brain is significantly smaller than in other tissues (115 vs 130 kDa), whereas beta-subunits (94 kDa) are identical. We suggest that brain insulin receptors represent a subtype regarding their binding function, whereas their enzyme function is more conserved. |
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Keywords: | Hormone receptor Receptor subunit Phosphorylation Rat brain cortex synaptosome |
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