Biophysical Society Thematic Meeting | Tutzing 2026

Single-Molecule FRET: The Next 30 Years

Wednesday Speaker Abstracts

RESOLVING MET RECEPTOR ACTIVATION IN CELLS BY SINGLE-MOLECULE FRET Yunqing Li 1 ; Serena M Arghittu 2,3 ; Marina S Dietz 1 ; Petra Freund 1 ; Hans-Dieter Barth 1 ; Hartmut H Niemann 4 ; Roberto Covino 2,3,5 ; Mike Heilemann 1,3 ; 1 Goethe University Frankfurt, Institute of Physical and Theoretical Chemistry, Frankfurt am Main, Germany 2 Frankfurt Institute for Advanced Studies, Frankfurt am Main, Germany 5 Goethe-University Frankfurt, Institute of Computer Science, Frankfurt am Main, Germany Membrane receptors initiate cellular signaling through ligand-induced structural rearrangements, dimerization, and dynamic interactions within the plasma membrane. However, these early activation events are difficult to resolve in their native cellular environment, where receptor complexes are heterogeneous, transient, and not synchronized. We apply single-molecule FRET to investigate the early activation of the receptor tyrosine kinase MET by the bacterial invasion protein internalin B. By combining site-specific fluorescence labeling, in situ smFRET, and molecular dynamics simulations, we resolved the nanoscale organization of ligand-bound MET dimers directly in cells and identified an antiparallel dimer assembly. To further access receptor dynamics in living cells, we combined smFRET recovery after photobleaching with single particle tracking. This approach allowed us to follow individual MET complexes over time and quantify key biophysical parameters of receptor activation, including dimer lifetime, lateral diffusion, and confinement within the plasma membrane. Together, our work demonstrates how smFRET can provide structural and dynamic insight into transient membrane receptor signaling complexes in their native cellular context. 3 IMPRS on Cellular Biophysics, Frankfurt am Main, Germany 4 Bielefeld University, Department of Chemistry, Bielefeld, Germany

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