Figure 5. TgTRPPL-2 permeates Ca²⁺.

(A) Representative traces of currents recorded at −80 mV in the presence of 1.8 mM Ca²⁺ inside the pipette (Solution D, Supplementary file 4) of nuclear extracts from control, TgTRPPL-2-, or polycystin 2 (PC2)-expressing cells. Traces are a representation of 2 s. (B) Current-voltage relationship comparing single-channel current amplitude of TgTRPPL-2 cells in 1.8 mM in KCl (blue) or CsCl (green) buffer. Inset: slope conductance of TgTRPPL-2 in the different conditions analyzed. (C) Calculated open probability of TgTRPPL-2-expressing cells in the presence of 1.8 mM Ca²⁺ in a KCl (blue) or CsCl (green) buffer. (D) Average time of channel openings (dwell time) of TgTRPPL-2-expressing cells in the presence of 1.8 mM Ca²⁺ in a KCl (blue) or CsCl (green). *p<0.04. Values are means ± SEM.

Figure 5—figure supplement 1. Measurement of endoplasmic reticulum (ER) calcium of HEK-3KO cells expressing TgTRPPL-2.

(A) Fluorescence of ER calcium in ER-RFP-HEK (Control) vs. TgTRPPL-2-HEK (TgTRPPL-2) in a high calcium-potassium solution of patched nuclear membranes while the membrane is depolarized. (B) Quantification of fluorescence of patched cells while the membrane is depolarized from −80 to +40 mV in a high calcium-potassium solution. (C) Quantification of the slope of fluorescence in (B) comparing TgTRPPL-2-HEK-3KO cells versus control cells. Slope of the fluorescence was quantified based on the five technical replicates of the artificial membrane depolarization in each cell analyzed. Asterisk indicate p-value for significant difference. Values represent the mean of the slope shown in (B). *p<0.01. (D) Quantification of fluorescence of patched cells while the membrane is depolarized from −80 to +40 mV in a high calcium-cesium solution. (E) Quantification of the slope of fluorescence in (D) comparing TgTRPPL-2-HEK-3KO cells versus control cells. The slope was quantified for the five technical replicates of patched membranes. Asterisk indicates p-value for significant difference. Values represent the mean of the slope shown in (D). *p<0.03. (F) Comparison of the fluorescence of patched nuclear extract of TgTRPPL-2-HEK cells while the membrane was artificially depolarized. (G) Quantification of the slope of fluorescence of patched TgTRPPL-2-HEK-3KO nuclear extracts in different experimental conditions. Slope of the fluorescence was quantified based on the five technical replicates of the artificial membrane depolarization in each cell analyzed.