title: Two new monoclonal antibodies against the alpha subunit of the human insulin-like growth factor-I receptor.
abstract: Recently, we have reported three monoclonal antibodies (mAbs) against purified human placental insulin-like growth factor (IGF)-I receptors. These antibodies, in contrast to the well-studied mAb alpha IR-3, stimulate binding of IGF-I and IGF-II to the receptor and DNA synthesis as well [Xiong, et al., Proc. Natl. Acad. Sci. U.S.A. 1992(89), 5356]. Here we describe two additional mAbs, 1H7 and 2C8, against the IGF-I receptor that have characteristics different from either alpha IR-3 or our previously reported mAbs. Both 1H7 and 2C8 bind to the alpha subunit of the IGF-I receptor as determined by immunoblotting. MAb 1H7 inhibited the binding of IGF-I and IGF-II to the IGF-I receptor while 2C8 had no effect on the binding of either ligand to the receptor. When their effects on DNA synthesis were examined using NIH 3T3 cells expressing human IGF-I receptors, 1H7 inhibited basal and IGF-I- or IGF-II-stimulated DNA synthesis whereas 2C8 stimulated basal DNA synthesis but provided no synergism in the presence of IGF-I or IGF-II.
authors.affiliation: Department of Molecular Genetics, Beckman Research Institute of the City of Hope, Duarte, CA 91010.
authors.forename: S L
authors.initials: SL
authors.lastname: Li
authors.forename: J
authors.initials: J
authors.lastname: Kato
authors.forename: I B
authors.initials: IB
authors.lastname: Paz
authors.forename: J
authors.initials: J
authors.lastname: Kasuya
authors.forename: Y
authors.initials: Y
authors.lastname: Fujita-Yamaguchi
mesh_terms: D016475:3T3 Cells; D000818:Animals; D000911:Antibodies, Monoclonal; D000918:Antibody Specificity; D005260:Female; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000378:metabolism; D007335:Insulin-Like Growth Factor II / Q000378:metabolism; D046911:Macromolecular Substances; D051379:Mice; D010766:Phosphorylation; D010920:Placenta; D011247:Pregnancy; D011487:Protein Conformation; D017526:Receptor, IGF Type 1 / Q000276:immunology* / Q000378:metabolism*; D015398:Signal Transduction; D013002:Somatomedins / Q000378:metabolism*
chemical_list: D000911:Antibodies, Monoclonal; D046911:Macromolecular Substances; D013002:Somatomedins; D007334:Insulin-Like Growth Factor I; D007335:Insulin-Like Growth Factor II; D017526:Receptor, IGF Type 1