title: The type V transforming growth factor beta receptor is the putative insulin-like growth factor-binding protein 3 receptor.
abstract: Insulin-like growth factor-binding protein 3 (IGFBP-3) has been shown to inhibit cell growth by IGF-dependent and -independent mechanisms. The putative cell-surface IGFBP-3 receptor that mediates the IGF-independent growth inhibition has not been identified. Here we show that recombinant human IGFBP-3 inhibits 125I-transforming growth factor (TGF)-beta1 binding to the type V TGF-beta receptor (Mr 400,000) in mink lung epithelial cells. We also demonstrate that the approximately 400-kDa 125I-IGFBP-3 affinity-labeled putative IGFBP-3 receptor is immunoprecipitated by specific antiserum to the type V TGF-beta receptor. The 125I-IGFBP-3 affinity labeling of the putative receptor and IGFBP-3-induced growth inhibition as measured by DNA synthesis in these cells is blocked by a TGF-beta1 peptide antagonist. The 125I-IGFBP-3 affinity-labeled putative receptor can only be detected in cells expressing the type V TGF-beta receptor, but not in cells lacking the type V TGF-beta receptor. These results indicate that the type V TGF-beta receptor is the putative IGFBP-3 receptor and that IGFBP-3 is a functional ligand for the type V TGF-beta receptor.
authors.affiliation: Department of Biochemistry and Molecular Biology, St. Louis University School of Medicine, St. Louis, Missouri 63104, USA.
authors.forename: S M
authors.initials: SM
authors.lastname: Leal
authors.forename: Q
authors.initials: Q
authors.lastname: Liu
authors.forename: S S
authors.initials: SS
authors.lastname: Huang
authors.forename: J S
authors.initials: JS
authors.lastname: Huang
mesh_terms: D000818:Animals; D006801:Humans; D018972:Insulin-Like Growth Factor Binding Protein 3 / Q000378:metabolism* / Q000494:pharmacology; D008907:Mink; D018125:Receptors, Transforming Growth Factor beta / Q000378:metabolism*; D016212:Transforming Growth Factor beta / Q000378:metabolism / Q000494:pharmacology; D014407:Tumor Cells, Cultured
chemical_list: D018972:Insulin-Like Growth Factor Binding Protein 3; D018125:Receptors, Transforming Growth Factor beta; D016212:Transforming Growth Factor beta