Figure 4. Depletion of native PIP 2 with... | Rockefeller University Press

Figure 4.

$Figure 4. Depletion of native PIP2 with CiVSP alters Elk1 gating kinetics. (A) Normalized Elk1 current traces recorded at 60 mV on cell patches from an Elk1 control and Elk1 + CiVSP. Repeated 2-s steps to 60 mV were delivered at 6-s intervals, and the 1st, 2nd, and 20th sweeps are shown for comparison. (B) Activation time constants at various voltages determined for Elk1 + CiVSP on cell patches (n = 5) and compared with Elk1 on cell and excised controls from Fig. 1 F. The on-cell time constant significantly decreased at all voltages measured (P < 0.001; t test) with CiVSP coexpression. (C) Normalized tail current traces at −100 mV after 2-s prepulse to 60 mV. The first sweep is shown for each condition, and the tail shape did not change with further repeated sweeps (dotted line, zero current). (D) Deactivation time course measured as fractional tail current remaining 60 ms after repolarization to −100 mV after a 2-s prepulse to 60 mV (n = 34, 16, and 39 for on-cell control, + CiVSP, and excised control, respectively; ***, P < 0.001; t test). (E) On-cell G-V curves for Elk1 controls (black; n = 5) and +CiVSP (red; n = 4) recorded from the typical −100-mV hold (squares) and with a 1-s 60-mV prepulse (circles). Curves show single Boltzmann fits, and G-V mode shift values (circle V50 − square V50) are reported in Table 3. All data are reported as mean ± SEM.$

Depletion of native PIP₂ with CiVSP alters Elk1 gating kinetics. (A) Normalized Elk1 current traces recorded at 60 mV on cell patches from an Elk1 control and Elk1 + CiVSP. Repeated 2-s steps to 60 mV were delivered at 6-s intervals, and the 1st, 2nd, and 20th sweeps are shown for comparison. (B) Activation time constants at various voltages determined for Elk1 + CiVSP on cell patches (n = 5) and compared with Elk1 on cell and excised controls from Fig. 1 F. The on-cell time constant significantly decreased at all voltages measured (P < 0.001; t test) with CiVSP coexpression. (C) Normalized tail current traces at −100 mV after 2-s prepulse to 60 mV. The first sweep is shown for each condition, and the tail shape did not change with further repeated sweeps (dotted line, zero current). (D) Deactivation time course measured as fractional tail current remaining 60 ms after repolarization to −100 mV after a 2-s prepulse to 60 mV (n = 34, 16, and 39 for on-cell control, + CiVSP, and excised control, respectively; ***, P < 0.001; t test). (E) On-cell G-V curves for Elk1 controls (black; n = 5) and +CiVSP (red; n = 4) recorded from the typical −100-mV hold (squares) and with a 1-s 60-mV prepulse (circles). Curves show single Boltzmann fits, and G-V mode shift values (circle V₅₀ − square V₅₀) are reported in Table 3. All data are reported as mean ± SEM.