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dc.contributor.advisorShimizu, Noboyoshien_US
dc.contributor.authorBehzadian, Mohammad Ali
dc.creatorBehzadian, Mohammad Alien_US
dc.date.accessioned2011-10-31T18:49:22Z
dc.date.available2011-10-31T18:49:22Z
dc.date.issued1984en_US
dc.identifier.urihttp://hdl.handle.net/10150/187716
dc.description.abstractA new approach has been introduced to characterize the epidermal growth factor receptors and their relation to the mechanism of cell growth control using hybrid cells made between human EGF responsive cells and mouse A9 cells incapable of EGF binding. BALBc mice were immunized with human carcinoma A431 cells carrying an extraordinary high number of EGF receptors; antisera were used to identify the human nature of EGF receptors in these hybrid cells. One of the hybrid lines, C2B5, that retains only one human chromosome, an X/7 translocation, and a nearly complete mouse parental genome was used to analyze the relationship of the binding ability and certain post-receptor functions to the cellular mitogenic response. It was shown that the ability to bind, internalize and degrade the ligand and/or its receptor is not sufficient for cells to respond to the mitogen. Spleen cells from mice immunized with A431 cells were fused with mouse myeloma P3NP cells. One of the isolated hybridoma lines, B4G7, secreted a monoclonal antibody of the IgG class which inhibits the binding of ¹²⁵I-EGF to A431 and human fibroblasts, but not of mouse 3T3 cells. This inhibition was partial (65-70%) and Scatchard analysis of the binding data suggested that antibody preferentially interacts with a low affinity class of EGf receptors. The antibody specifically precipitated EGF receptor from radiolabeled cells. This monoclonal antibody was crosslinked to subunit A of toxic ricin through a disulfide bond. The resulting conjugate inhibited protein synthesis of A431 cells at 4 x 10⁻¹¹M and exhibited substantial cell killing. Using this conjugate we isolated a variant of A431 cells, designated C1-B7, with approximately 30 times less EGF binding capacity. Contrary to the parental A431, this variant is resistant to EGF-induced suppression of cell growth and appears to have lost most of the low affinity receptors. The high affinity type EGF receptors retained by the variant are 170,000 Mr and susceptible to EGF-induced phosphorylation, presumably on tyrosine residues. In membrane prepared from this variant, besides the EGF receptor, a low molecular weight component of as yet unknown nature is highly phosphorylated in an EGF-independent manner.
dc.language.isoenen_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.subjectCells -- Growth -- Regulation.en_US
dc.subjectGrowth regulators.en_US
dc.titleGENETICS AND IMMUNOLOGICAL CHARACTERIZATION OF EPIDERMAL GROWTH FACTOR RECEPTORS AND THEIR RELATION TO THE MECHANISM OF CELL GROWTH CONTROL (MONOCLONAL ANTIBODY, TUMOR, RICIN TOXIN).en_US
dc.typetexten_US
dc.typeDissertation-Reproduction (electronic)en_US
dc.identifier.oclc691272464en_US
thesis.degree.grantorUniversity of Arizonaen_US
thesis.degree.leveldoctoralen_US
dc.contributor.committeememberAposhian, H. Vaskenen_US
dc.contributor.committeememberBernstein, Harrisen_US
dc.contributor.committeememberLindell, Thomas J.en_US
dc.contributor.committeememberKeck, K.en_US
dc.identifier.proquest8421964en_US
thesis.degree.disciplineCellular and Developmental Biologyen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.namePh.D.en_US
refterms.dateFOA2018-09-03T14:07:03Z
html.description.abstractA new approach has been introduced to characterize the epidermal growth factor receptors and their relation to the mechanism of cell growth control using hybrid cells made between human EGF responsive cells and mouse A9 cells incapable of EGF binding. BALBc mice were immunized with human carcinoma A431 cells carrying an extraordinary high number of EGF receptors; antisera were used to identify the human nature of EGF receptors in these hybrid cells. One of the hybrid lines, C2B5, that retains only one human chromosome, an X/7 translocation, and a nearly complete mouse parental genome was used to analyze the relationship of the binding ability and certain post-receptor functions to the cellular mitogenic response. It was shown that the ability to bind, internalize and degrade the ligand and/or its receptor is not sufficient for cells to respond to the mitogen. Spleen cells from mice immunized with A431 cells were fused with mouse myeloma P3NP cells. One of the isolated hybridoma lines, B4G7, secreted a monoclonal antibody of the IgG class which inhibits the binding of ¹²⁵I-EGF to A431 and human fibroblasts, but not of mouse 3T3 cells. This inhibition was partial (65-70%) and Scatchard analysis of the binding data suggested that antibody preferentially interacts with a low affinity class of EGf receptors. The antibody specifically precipitated EGF receptor from radiolabeled cells. This monoclonal antibody was crosslinked to subunit A of toxic ricin through a disulfide bond. The resulting conjugate inhibited protein synthesis of A431 cells at 4 x 10⁻¹¹M and exhibited substantial cell killing. Using this conjugate we isolated a variant of A431 cells, designated C1-B7, with approximately 30 times less EGF binding capacity. Contrary to the parental A431, this variant is resistant to EGF-induced suppression of cell growth and appears to have lost most of the low affinity receptors. The high affinity type EGF receptors retained by the variant are 170,000 Mr and susceptible to EGF-induced phosphorylation, presumably on tyrosine residues. In membrane prepared from this variant, besides the EGF receptor, a low molecular weight component of as yet unknown nature is highly phosphorylated in an EGF-independent manner.


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