Figure 2.

Functional evaluation of red-shifted cameleons in the ER. Permeabilized HeLa cells transfected with individual red-shifted sensors targeted to the ER were recorded in an extracellular Ca²⁺-free solution and in a 2 mM Ca²⁺ containing environment, respectively. Representative curves showing FRET signals of each indicator excited at 420, 450, 460, 470, 480 or 490 nm and emissions were collected from either (A) D1ERGO-Cam1 (dark grey curve), D1ERGO-Cam2 (green curve), D1ERRG-Cam1 (pink curve), D1ERRG-Cam2 (purple curve), D1ERGR (light grey curve), D1ERTG (violet curve) or (B) D1ERRC (light green curve), D1ERCR (grey curve), D1ERGmR2 (black curve), D1ERmR2G (dark red curve), D1ERmR2C (blue curve) or D1ERCmR2 (red curve).