title: Structural snapshots of full-length Jak1, a transmembrane gp130/IL-6/IL-6Rα cytokine receptor complex, and the receptor-Jak1 holocomplex.
abstract: The shared cytokine receptor gp130 signals as a homodimer or heterodimer through activation of Janus kinases (Jaks) associated with the receptor intracellular domains. Here, we reconstitute, in parts and whole, the full-length gp130 homodimer in complex with the cytokine interleukin-6 (IL-6), its alpha receptor (IL-6Rα) and Jak1, for electron microscopy imaging. We find that the full-length gp130 homodimer complex has intimate interactions between the trans- and juxtamembrane segments of the two receptors, appearing to form a continuous connection between the extra- and intracellular regions. 2D averages and 3D reconstructions of full-length Jak1 reveal a three lobed structure comprising FERM-SH2, pseudokinase, and kinase modules possessing extensive intersegmental flexibility that likely facilitates allosteric activation. Single-particle imaging of the gp130/IL-6/IL-6Rα/Jak1 holocomplex shows Jak1 associated with the membrane proximal intracellular regions of gp130, abutting the would-be inner leaflet of the cell membrane. Jak1 association with gp130 is enhanced by the presence of a membrane environment.
authors.affiliation: Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305, USA.
authors.forename: Patrick J
authors.initials: PJ
authors.lastname: Lupardus
authors.forename: Georgios
authors.initials: G
authors.lastname: Skiniotis
authors.forename: Amanda J
authors.initials: AJ
authors.lastname: Rice
authors.forename: Christoph
authors.initials: C
authors.lastname: Thomas
authors.forename: Suzanne
authors.initials: S
authors.lastname: Fischer
authors.forename: Thomas
authors.initials: T
authors.lastname: Walz
authors.forename: K Christopher
authors.initials: KC
authors.lastname: Garcia
mesh_terms: D015060:1,2-Dipalmitoylphosphatidylcholine / Q000737:chemistry; D050822:Cytokine Receptor gp130 / Q000737:chemistry*; D006801:Humans; D053613:Janus Kinase 1 / Q000737:chemistry*; D008854:Microscopy, Electron; D008958:Models, Molecular; D049329:Nanostructures; D055503:Protein Multimerization; D020836:Protein Structure, Quaternary; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000737:chemistry*
chemical_list: C494199:IL6ST protein, human; D011993:Recombinant Fusion Proteins; D050822:Cytokine Receptor gp130; D015060:1,2-Dipalmitoylphosphatidylcholine; C507904:JAK1 protein, human; D053613:Janus Kinase 1