Binding of an antagonistic monoclonal antibody to an intact and fragmented EGF-receptor polypeptide |
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| Authors: | U Murthy A Basu U Rodeck M Herlyn A H Ross M Das |
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| Affiliation: | 1. Department of Biochemistry and Biophysics, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104 USA;2. The Wistar Institute, Philadelphia, Pennsylvania 19104 USA;1. Scott-Ritchey Research Center, College of Veterinary Medicine, Auburn University, Auburn, AL 36849 USA;2. Laboratory Animal Health, College of Veterinary Medicine, Auburn University, Auburn, AL 36849, USA;3. Department of Animal and Rangeland Sciences, Oregon State University, Corvallis, OR 97331, USA;4. Department of Pathobiology, College of Veterinary Medicine, Auburn University, Auburn, AL 36849, USA;5. Department of Anatomy, Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, Auburn, AL 36849, USA;1. Sakarya University Training and Research Hospital, Department of Hematology, Sakarya, Turkey;2. Sakarya University, Department of Hematology, 54050, Sakarya, Turkey;3. University of Health Sciences, Ankara Oncology Training and Research Hospital, Department of Hematology & Apheresis Unit, Ankara, Turkey;4. Pamukkale University, Department of Hematology, Denizli, Turkey;5. University of Health Sciences, GaziYasargil Training and Research Hospital, Department of Hematology, Diyarbakir, Turkey;6. University of Health Sciences, Kayseri City Training and Research Hospital, Department of Hematology & Apheresis Unit, Kayseri, Turkey;7. University of Health Sciences, DiskapiYildirimBeyazit Training and Research Hospital, Department of Hematology, Ankara, Turkey;8. Yuzuncu YilUniversity, Department of Hematology, Van, Turkey;9. Near East University, School of Medicine, Department of Internal Medicine, Division of Hematology, Nicosia, Cyprus;10. Medical Park Antalya Hospital, Department of Hematology, Antalya, Turkey;11. Ankara YildirimBeyazit University, School of Medicine, Department of Internal Medicine, Division of Hematology, Ankara, Turkey |
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| Abstract: | A murine monoclonal antibody (No. 425) raised against human A431 carcinoma cells specifically immunoprecipitates the 170,000 molecular weight epidermal growth factor (EGF)-receptor from extracts of A431 cells as well as from extracts of human placenta and cultured fibroblasts, but does not recognize the murine receptor. Binding to the external domain of the human EGF-receptor was indicated by indirect immunofluorescent staining of fixed nonpermeable cells. The antibody binds to both glyco- and aglycoreceptor forms, indicating that the epitope is a part of the polypeptide chain. Binding of the antibody to the receptor is conformation dependent; i.e., denatured receptors lacking EGF-binding activity are not recognized by the antibody. The results of antibody binding studies indicate that the epitope is closely linked to the EGF binding active site, and is common to both high- and low-affinity EGF-receptors. Interaction of this epitope with the antibody inhibits EGF binding and bioactivity, and triggers receptor down-regulation, but does not generate EGFlike kinase-stimulatory or mitogenic responses either in vitro or in vivo. The antibody was tested for its ability to bind to domain-sized fragments of the 170-kDa EGF-receptor. It can recognize both the proteolytically generated 110-kDa EGF binding peptide, and a soluble 100-kDa EGF-receptor secreted by A431 cells. This indicates that the epitope recognized this antibody retains its conformation after proteolytic separation of the EGF binding domain from the rest of the receptor molecule. |
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