Skip to main content
. 2019 May 2;8:e45851. doi: 10.7554/eLife.45851

Figure 3. Mutations of Q276 diminish SSD.

(A) Values of apparent pHSSD and (B) apparent pH50A of substitutions in position 276. Curves represent fits of data points (n = 5–8 independent measurements) to the Hill equation. (C) Current traces of Q276G activated sequentially with solutions of the indicated pH (bars above the trace) in the presence of 2 mM Ca2+ and nominal 0 mM Ca2+. Pre-conditioning protons do not induce SSD in any of the two conditions. (D) The absence of Ca2+ in the activating solution increases the apparent affinity for protons from pH50A6.8 to 7.0.

Figure 3.

Figure 3—figure supplement 1. Q276G channels are insensitive to agents that modulate SSD.

Figure 3—figure supplement 1.

(A) The tarantula toxin Pctx1 (5 nM) in preconditioning solutions of three different pH values does not change the Q276G response to pH 6.5. (B) 0.25 mM Spermine (SPM) in the bathing solution does not change the absence of SSD in Q276G but shifts the apparent pH50A from 6.8 to 6.5. (C) pH-dependence of Q276G activation in the presence of 0.25 mM spermine.