Figure 5. Regulation of TRPV1 by phosphoinositides.
(A–B) Capsaicin (10 μM)- or heat-evoked currents were observed in minimal TRPV1-containing proteoliposomes lacking phosphoinostides.
(C) With the exception of PIP3 (4%), phosphoinositides (4%) produced rightward shift in capsaicin dose-response curve relative to minimal proteoliposomes (EC50 =0.33, 0.29, 0.88, 1.36, and 1.63 μM for no phosphoinositides, PIP3, PIP2, PI, and PI4P, respectively).
(D) Inclusion of various phosphoinositides (4%) produced marked rightward shift in thermal response profiles. TRPV1 proteoliposomes without phosphoinositides or with PIP3 (4%) exhibit thermal response profiles characteristic of sensitized channels. Traces in (D) show averaged profiles (n > 7 patches per condition; individual traces shown in Figure S4A-G).
(E) Thermal activation thresholds for curves shown in (D) Error bar denotes mean ± s.d., *p<0.0001, Student’s t-test, n > 7 per condition.