Rescue of ligand binding of a mutant IGF-I receptor by complementation |
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Authors: | Chakravarty Anders Hinrichsen Jane Whittaker Linda Whittaker Jonathan |
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Institution: | Receptor Biology Laboratory, Novo Nordisk A/S, Hagedorn Research Institute, DK-2820 Gentofte, Denmark. |
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Abstract: | The IGF-I receptor binds IGF-I with complex kinetics characterized by a curvilinear Scatchard plot, suggesting receptor heterogeneity and apparent negative cooperativity. To explore the molecular mechanisms underlying these properties, we have characterized the binding of a hybrid receptor formed from a wild-type receptor monomer and a mutant receptor monomer devoid of binding activity. Receptor hybrids were generated by transient co-transfection of cDNAs encoding wild-type and mutant receptors with unique epitope tags. Hybrid receptors were purified from transfected cells by sequential immuno-affinity chromatography and their ligand-binding properties were determined. Complementation produced a hybrid with near wild-type affinity. Dissociation studies demonstrated that the hybrid did not exhibit negative cooperativity. |
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Keywords: | IGF-I Mutant Hybrid receptor Complementation Affinity Dissociation Negative cooperativity |
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