Effects of coexpressing TRIC-A or TRIC-B with RyR2 on the currents elicited by voltage ramps. (A) Representative current fluctuations from individual experiments after incorporating vesicles from HEK293 cells expressing only RyR2 in which a single RyR2 channel was incorporated (black) or when a background current was detected (green). The black (RyR2-only) and green (background current) arrows indicate the E_rev for the individual experiment. (B) Representative currents from individual experiments after incorporating vesicles from HEK293 cells coexpressing RyR2+TRIC-A (blue) or coexpressing RyR2+TRIC-B (red) into the bilayer. The blue (RyR2+TRIC-A) and red (RyR2+TRIC-B) arrows indicate the E_rev for the corresponding experiment. Vesicles were incubated with the bilayer for 5–10 min in 740 mM cytosolic:210 mM luminal KCl gradient to allow multiple fusion events (evidenced by step changes in conductance) to occur. Vesicle fusion was halted by perfusing the cytosolic chamber with 210 mM KCl. The 740 mM cytosolic:210 mM luminal KCl gradient was then reapplied. The bilayers were held at 0 mV and then switched to −50 mV for 1 s before applying the voltage ramp (red) from −50 to +50 mV.