Comparison of insulin-like growth factor I receptor and insulin receptor purified from human placental membranes
| Autor: | T R LeBon, Yoko Fujita-Yamaguchi, M Tsubokawa, William J. Henzel, D Koyal, J. Ramachandran, S Kathuria |
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Macromolecular Substances
Placenta Interleukin 5 receptor alpha subunit Biochemistry Binding Competitive Interleukin 10 receptor alpha subunit Estrogen-related receptor alpha Liver X receptor beta Pregnancy Insulin receptor substrate Enzyme-linked receptor Humans 5-HT5A receptor Amino Acid Sequence Molecular Biology biology Cell Membrane Receptors Somatomedin Cell Biology Receptor Insulin Molecular Weight Insulin receptor Dithiothreitol Kinetics biology.protein Female |
| Zdroj: | Europe PubMed Central |
| ISSN: | 7685-7689 |
| Popis: | Insulin-like growth factor (IGF)-I receptor purified from human placental membranes as previously described (LeBon, T. R., Jacobs, S., Cuatrecasas, P., Kathuria, S., and Fujita-Yamaguchi, Y. (1986) J. Biol. Chem. 261, 7685-7689) was characterized. The IGF-I receptor was similar to the insulin receptor with respect to subunit structure (beta-alpha-alpha-beta), apparent sizes of deglycosylated alpha (Mr = approximately 88,000) and beta (Mr = approximately 67,000) subunits, and amino acid composition of the subunits. Monoclonal antibody specific to each receptor recognized its own receptor whereas polyclonal anti-human insulin receptor antibody cross-reacted with the IGF-I receptor, indicating that the receptors share one or more antigenic sites. Further characterization of the purified IGF-I receptor tyrosine-protein kinase activity indicated that by analogy with the insulin receptor the monomeric alpha beta form of the IGF-I receptor appears to have higher kinase activity than the intact receptor in the alpha 2 beta 2 form. The most significant difference between the two receptors was found in the N-terminal amino acid sequences of their alpha subunits, which apparently show 60% identity. The IGF-I receptor alpha subunit lacks residues corresponding to the N-terminal 4 amino acids of the insulin receptor alpha subunit. These results provide the first direct proof that the IGF-I receptor is a molecule distinct from the insulin receptor despite numerous similarities. |
| Databáze: | OpenAIRE |
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