title: Signaling conformations of the tall cytokine receptor gp130 when in complex with IL-6 and IL-6 receptor.
abstract: gp130 is a shared cytokine signaling receptor and the founding member of the 'tall' class of cytokine receptors. A crystal structure of the ligand-binding domains of gp130 in complex with human interleukin-6 (IL-6) and its a-receptor (IL-6Ralpha) revealed a hexameric architecture in which the gp130 membrane-distal regions were approximately 100 A apart, in contrast to the close apposition seen between short cytokine receptor complexes. Here we used single-particle EM to visualize the entire extracellular hexameric IL-6-IL-6Ralpha-gp130 complex, containing all six gp130 domains. The structure reveals that gp130 is bent such that the membrane-proximal domains of gp130 are close together at the cell surface, enabling activation of intracellular signaling. Variation in the receptor bend angles suggests a possible conformational transition from open to closed states upon ligand binding; this transition is probably representative of the other tall cytokine receptors.
authors.affiliation: Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, Massachusetts 02115, USA.
authors.forename: Georgios
authors.initials: G
authors.lastname: Skiniotis
authors.forename: Martin J
authors.initials: MJ
authors.lastname: Boulanger
authors.forename: K Christopher
authors.initials: KC
authors.lastname: Garcia
authors.forename: Thomas
authors.initials: T
authors.lastname: Walz
mesh_terms: D015703:Antigens, CD / Q000737:chemistry* / Q000378:metabolism; D001665:Binding Sites; D050822:Cytokine Receptor gp130; D006801:Humans; D007091:Image Processing, Computer-Assisted; D015850:Interleukin-6 / Q000737:chemistry / Q000378:metabolism*; D008024:Ligands; D008562:Membrane Glycoproteins / Q000737:chemistry* / Q000378:metabolism; D008958:Models, Molecular; D016133:Polymerase Chain Reaction; D011487:Protein Conformation; D019947:Receptors, Interleukin-6 / Q000737:chemistry* / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D015398:Signal Transduction
chemical_list: D015703:Antigens, CD; C494199:IL6ST protein, human; D015850:Interleukin-6; D008024:Ligands; D008562:Membrane Glycoproteins; D019947:Receptors, Interleukin-6; D011994:Recombinant Proteins; D050822:Cytokine Receptor gp130