title: Preformed oligomeric epidermal growth factor receptors undergo an ectodomain structure change during signaling.
abstract: Fluorescence resonance energy transfer (FRET) was used to reveal aspects of the mechanism of signal transduction by epidermal growth factor receptors (EGFR). The superpositions of epidermal growth factor (EGF), transforming growth factor-alpha (TGFalpha) and an antibody fragment (29.1) to the carbohydrate extremity of the receptor's ectodomain as measured by FRET, show that 14% of EGFRs in A431 cells are oligomerized before growth factor binding. After binding growth factor and signaling, these oligomers dissociate before releasing growth factor. Time courses of the FRET-derived distances between constitutively oligomerized EGFRs during signal transduction show a transient structural change in the extracellular domain, which occurs simultaneously with the production of intracellular Ca2+ signals. The FRET measurements also show a slow increase in oligomerization of EGFR monomers after growth factor binding. The structural change found in the extracellular domain of oligomeric EGFRs is similar to that shown by others for EPO, Neu, Fas, and tumor necrosis factor receptors, and may therefore be a common property of the transduction of the receptor-mediated signals.
authors.affiliation: CLRC Daresbury Laboratory, Warrington WA4 4AD, United Kingdom.
authors.forename: Marisa
authors.initials: M
authors.lastname: Martin-Fernandez
authors.forename: David T
authors.initials: DT
authors.lastname: Clarke
authors.forename: Mark J
authors.initials: MJ
authors.lastname: Tobin
authors.forename: Samantha V
authors.initials: SV
authors.lastname: Jones
authors.forename: Gareth R
authors.initials: GR
authors.lastname: Jones
mesh_terms: D020013:Calcium Signaling / Q000502:physiology*; D002460:Cell Line; D004735:Energy Transfer; D066246:ErbB Receptors / Q000737:chemistry* / Q000502:physiology*; D005456:Fluorescent Dyes; D017930:Genes, Reporter; D049452:Green Fluorescent Proteins; D006801:Humans; D007128:Immunoglobulin Fragments; D007700:Kinetics; D008164:Luminescent Proteins / Q000032:analysis / Q000235:genetics; D021122:Protein Subunits; D015398:Signal Transduction / Q000502:physiology*; D013050:Spectrometry, Fluorescence; D016211:Transforming Growth Factor alpha / Q000502:physiology; D014407:Tumor Cells, Cultured
chemical_list: D005456:Fluorescent Dyes; D007128:Immunoglobulin Fragments; D008164:Luminescent Proteins; D021122:Protein Subunits; D016211:Transforming Growth Factor alpha; D049452:Green Fluorescent Proteins; D066246:ErbB Receptors