title: Association of eukaryotic translation initiation factor eIF2B with fully solubilized CXCR4.
abstract: Chemokine receptors are key regulators of leukocyte trafficking but also have an important role in development, tumor growth, and metastasis. Among the chemokine receptors, CXCR4 is the only one that leads to perinatal death when genetically ablated in mice, indicating a more-widespread function in development. To identify pathways that are activated downstream of CXCR4, a solubilization protocol was elaborated, which allows for the isolation of the endogenous receptor from human cells in its near-native conformation. Solubilized CXCR4 is recognized by the conformation-sensitive monoclonal antibody 12G5 and retains the ability to bind CXCL12 in solution, which was abolished in the presence of receptor antagonists. Mass spectrometry of CXCR4 immunoprecipitates revealed a specific interaction with the pentameric eukaryotic translation initiation factor 2B. The observation that the addition of CXCL12 leads to the dissociation of eukaryotic translation initiation factor 2B from CXCR4 suggests that stimulation of the receptor may trigger the local protein synthesis required for efficient cell movement.
authors.affiliation: Institute for Research in Biomedicine, Bellinzona, Switzerland; and.
authors.forename: Elena
authors.initials: E
authors.lastname: Palmesino
authors.affiliation: Institute for Research in Biomedicine, Bellinzona, Switzerland; and.
authors.forename: Tiziana
authors.initials: T
authors.lastname: Apuzzo
authors.affiliation: Institute for Research in Biomedicine, Bellinzona, Switzerland; and.
authors.forename: Sylvia
authors.initials: S
authors.lastname: Thelen
authors.affiliation: Protein and Metabolite Technologies, F. Hoffmann-La Roche Ltd, Pharmaceutical Sciences Roche Innovation Center, Basel, Switzerland.
authors.forename: Bernd
authors.initials: B
authors.lastname: Mueller
authors.affiliation: Protein and Metabolite Technologies, F. Hoffmann-La Roche Ltd, Pharmaceutical Sciences Roche Innovation Center, Basel, Switzerland.
authors.forename: Hanno
authors.initials: H
authors.lastname: Langen
authors.affiliation: Institute for Research in Biomedicine, Bellinzona, Switzerland; and marcus.thelen@irb.usi.ch.
authors.forename: Marcus
authors.initials: M
authors.lastname: Thelen
mesh_terms: D000595:Amino Acid Sequence; D002460:Cell Line; D002853:Chromatography, Liquid; D020717:Eukaryotic Initiation Factor-2B / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D047468:Immunoprecipitation; D010455:Peptides / Q000737:chemistry / Q000378:metabolism; D011485:Protein Binding; D019718:Receptors, CXCR4 / Q000378:metabolism*; D012995:Solubility; D053719:Tandem Mass Spectrometry
chemical_list: D020717:Eukaryotic Initiation Factor-2B; D010455:Peptides; D019718:Receptors, CXCR4
keywords: CXCL12; GPCR; signal transduction; solubilization