Preassembly of interleukin 2 (IL-2) receptor subunits on resting Kit 225 K6 T cells and their modulation by IL-2, IL-7, and IL-15: A fluorescence resonance energy transfer study

摘要: Assembly and mutual proximities of α, β, γc subunits the interleukin 2 receptors (IL-2R) in plasma membranes Kit 225 K6 T lymphoma cells were investigated by fluorescence resonance energy transfer (FRET) using fluorescein isothiocyanate- Cy3-conjugated monoclonal antibodies (mAbs) that directed against IL-2Rα, IL-2Rβ, IL-2R. The cell-surface distribution was analyzed at nanometer scale (2–10 nm) FRET on a cell-by-cell basis. probed resting phase after coculture with saturating concentrations IL-2, IL-7, IL-15. data from donor- acceptor-labeled IL-2Rβ-α, γ-α, γ-β pairs demonstrated close proximity all to each other membrane cells. These do not appear represent mAb-induced microaggregation, because measurements Fab fragments mAbs gave similar results. relative meaningfully modulated binding Based analysis topology three surface can be best described “triangular model” absence added interleukins. IL-2 strengthens bridges between subunits, making triangle more compact. IL-7 IL-15 act opposite direction opening possibly they associate their private specific α β and/or IL-2R complex. suggest are already colocalized require cytokine-induced redistribution. This colocalization is significantly relevant interleukins cytokine-specific manner.