Fig. 4: H+-mediated conformational change of TD receptors for transmembrane FRET and photocleavage.
From: Oriented triplex DNA as a synthetic receptor for transmembrane signal transduction
a Schematic diagram illustrating the pH-dependent conformational transition of the TD receptor, leading to FRET-based signal transduction. b Normalized fluorescence spectra showing increased FRET efficiency at 675 nm as the pH decreases from 8.0 to 5.0, indicating triplex formation. Inset: Quantitative analysis of the FRET efficiency (the Fa/Fd ratio, 675 nm to 570 nm). Chol3-TD-FRET: 1 μM. Data are presented as mean ± s.d. (n = 3 independent samples). c Confocal fluorescence images of a single GUV showing strong Cy5 fluorescence at pH 5.5, confirming FRET occurrence due to triplex formation. d Schematic representation of the photocleavable linker (PC-linker) system used to validate transmembrane translocation of the signal module. e, f Fluorescence intensity changes in the exterior and interior of vesicles at high pH (7.5) upon UV irradiation, showing signal output remaining outside. g, h Fluorescence intensity changes in the exterior and interior of vesicles at low pH (5.5) upon UV irradiation, demonstrating signal translocation to the interior. Each experiment was independently repeated three times, with consistent results. Data in (f, h) are presented as mean ± s.d. (n = 3 independent GUVs). Chol3-TD-PC-Cy3: 2 μM. Scale bars (e, g), 5 μm. a.u. arbitrary units.
