Fig. 4.

Ca²⁺ activates TRPM5 single channels in inside-out patches. (A) TRPM5 single-channel activity in inside-out patches of HEK-293 cells. Ramps with no channel activity were used for leak correction. The top profile shows excision of the patch into 0 Ca²⁺ solution; the middle and bottom profiles are consecutive examples of channel activity evoked by 300 nM Ca²⁺.(B) Ensemble I/V curve of TRPM5 single channels (75 ramps) and control cells (WT HEK-293; 98 ramps) during 300 nM Ca²⁺ exposure. (C) Current–voltage relationship of TRPM5 single channels. Each point reflects the average of 15–25 events per voltage from five patches. The slope yields a channel conductance of 25 pS. (D) Average charge measured before, during, and after exposure of TRPM5-expressing patches to 300 nM Ca²⁺ (same patches as in A–C, n = 5), assessed by integrating ramp currents between 0 mV and +100 mV.