Identification and initial characterization of insulin receptor-like immunoreactivity in human plasma
| Autor: | Lucia Frittitta, Riccardo Vigneri, A. Costantino, I. D. Goldfine, Vincenzo Papa, Vincenzo Pezzino, P. Russo |
|---|---|
| Rok vydání: | 1992 |
| Předmět: |
medicine.medical_specialty
Endocrinology Diabetes and Metabolism medicine.medical_treatment Clinical Biochemistry Radioimmunoassay Biochemistry Endocrinology Affinity chromatography Internal medicine medicine Humans Insulin Phosphorylation Polyacrylamide gel electrophoresis biology Biochemistry (medical) Autophosphorylation Protein-Tyrosine Kinases Receptor Insulin Wheat germ agglutinin Insulin receptor biology.protein Tyrosine kinase |
| Zdroj: | The Journal of Clinical Endocrinology & Metabolism. 74:1116-1121 |
| ISSN: | 1945-7197 0021-972X |
| DOI: | 10.1210/jcem.74.5.1314845 |
| Popis: | With a two-step purification procedure employing sequential affinity chromatography with insulin receptor monoclonal antibody followed by wheat germ agglutinin, we isolated from the plasma of two healthy individuals a material that reacted in a specific RIA for insulin receptors. This material produced dilution curves that were parallel to a human placental insulin receptor standard. This material also bound [125I]insulin; competition-inhibition curves revealed an ED50 of 0.3 nM, a value similar to that obtained with placental insulin receptors. The material purified from plasma was then labeled with [125I] Bolton-Hunter reagent, followed by polyacrylamide gel electrophoresis under reducing conditions and autoradiography. A band at 135 kilodaltons (kDa) was observed, corresponding to the alpha-subunit of the insulin receptor. Several bands ranging from 82-46 kDa were also detected. One or more of these fragments had intrinsic autophosphorylation activity, but only the 82-kDa band activity was responsive to insulin. In addition, employing the synthetic substrate poly(Glu4:Tyr1), no insulin-sensitive tyrosine kinase activity was present. These studies demonstrate, therefore, that insulin receptor-derived material is present in human plasma. This material retains high affinity insulin binding, but has an altered beta-subunit that is devoid of insulin-responsive tyrosine kinase activity. |
| Databáze: | OpenAIRE |
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