Figure 1.

A diagram summarizing the experimental scheme (not to scale). (Left) A home-built prism-type total internal reflection microscope with two-color fluorescence detection. (Right) The encapsulation assay. A supported lipid bilayer (a single membrane layer is depicted as one gray stripe) is first formed on a quartz coverslide (yellow) as a cushion. SUVs are then immobilized on the lipid cushion through biotin (brown dots)−streptavidin or neutravidin (blue) linker. The aHL pores on the SUV are shown also in blue. Encapsulated inside SUVs is the biomolecule (orange), depicted in folded and unfolded conformations at two and eight o’clock positions, respectively. The molecule is labeled with a donor (green) and an acceptor (red) which serve as FRET probes. The star shape represents the brighter fluorophore. Black circles represent the chemical agent (e.g., Mg²⁺ or ATP) relevant to the reaction under study.