title: Interleukin-11 signals through the formation of a hexameric receptor complex.
abstract: Interleukin-11 (IL-11) is a member of the gp130 family of cytokines. These cytokines drive the assembly of multisubunit receptor complexes, all of which contain at least one molecule of the transmembrane signaling receptor gp130. IL-11 has been shown to induce gp130-dependent signaling through the formation of a high affinity complex with the IL-11 receptor (IL-11R) and gp130. Site-directed mutagenesis studies have identified three distinct receptor binding sites of IL-11, which enable it to form this high affinity receptor complex. Here we present data from immunoprecipitation experiments, using differentially tagged forms of ligand and soluble receptor components, which show that multiple copies of IL-11, IL-11R, and gp130 are present in the receptor complex. Furthermore, it is demonstrated that sites II and III of IL-11 are independent gp130 binding epitopes and that both are essential for gp130 dimerization. We also show that a stable high affinity complex of IL-11, IL-11R, and gp130 can be resolved by nondenaturing polyacrylamide gel electrophoresis, and its composition verified by second dimension denaturing polyacrylamide gel electrophoresis. Results indicate that the three receptor binding sites of IL-11 and the Ig-like domain of gp130 are all essential for this stable receptor complex to be formed. We therefore propose that IL-11 forms a hexameric receptor complex composed of two molecules each of IL-11, IL-11R, and gp130.
authors.affiliation: Cancer Research Campaign Growth Factor Group, School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom.
authors.forename: V A
authors.initials: VA
authors.lastname: Barton
authors.forename: M A
authors.initials: MA
authors.lastname: Hall
authors.forename: K R
authors.initials: KR
authors.lastname: Hudson
authors.forename: J K
authors.initials: JK
authors.lastname: Heath
mesh_terms: D000818:Animals; D015703:Antigens, CD / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D001665:Binding Sites; D002460:Cell Line; D050822:Cytokine Receptor gp130; D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D007136:Immunoglobulins / Q000737:chemistry; D017370:Interleukin-11 / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology*; D053703:Interleukin-11 Receptor alpha Subunit; D046911:Macromolecular Substances; D008562:Membrane Glycoproteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D009154:Mutation / Q000235:genetics; D011233:Precipitin Tests; D011485:Protein Binding; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D016271:Proto-Oncogene Proteins c-myc / Q000378:metabolism; D018123:Receptors, Interleukin / Q000737:chemistry / Q000378:metabolism*; D053702:Receptors, Interleukin-11; D015398:Signal Transduction / Q000187:drug effects*; D013816:Thermodynamics
chemical_list: D015703:Antigens, CD; C508428:IL11RA protein, human; C494199:IL6ST protein, human; C508429:Il11ra1 protein, mouse; C494200:Il6st protein, mouse; D007136:Immunoglobulins; D017370:Interleukin-11; D053703:Interleukin-11 Receptor alpha Subunit; D046911:Macromolecular Substances; D008562:Membrane Glycoproteins; D016271:Proto-Oncogene Proteins c-myc; D018123:Receptors, Interleukin; D053702:Receptors, Interleukin-11; D050822:Cytokine Receptor gp130