Table 7. Changes in HV1 properties in C-terminal (219–273) mutants versus WT channels .
| Mutant | Species | Expr. system | I? | τ act | τ tail | ΔV thr | ΔpH slope | Selectivity | Other | Reference |
|---|---|---|---|---|---|---|---|---|---|---|
| S219P | hHV1 | COS/HEK wc | Yes | H+ | Musset et al., 2011 | |||||
| C249S | hHV1 | Loss of dimer formation | Li et al., 2015 | |||||||
| ΔC (T222stop) | hHV1 | HEK wc | Yes | 1 | 28 | Ramsey et al., 2010 | ||||
| ΔC (T222stop) | hHV1 | Yes | 0.15 | Weaker Zn2+ effects | Musset et al., 2010b | |||||
| ΔC | mHV1 (V216stop) | HEK wc | Yes | 0.34 | nc | nc | Loss of dimer formation | Koch et al., 2008 | ||
| ΔC | mHV1 (V216stop) | HEK wc | Yes | 0.15 | 0.16 | Okuda et al., 2016 | ||||
| ΔC | CiHV1 (D275stop) | Xenopus TEVC | Yes | 0.14 | 0.075 | Okuda et al., 2016 | ||||
| V220G/ K221G/T222G | mHV1 V216G/K217G/T218G | HEK wc | Loss of cooperative gating | Fujiwara et al., 2012 |
That numerical entries are shown does not imply that any given change was significant. HEK, HEK-293, HEK-293T, tsA, or HM1; COS, COS-7; Xenopus, Xenopus laevis oocyte; wc, whole cell; i-o, inside-out patch configuration; o-o, outside-out patch configuration; TEVC, two-electrode voltage clamp. Blank entries indicate that the parameter was not examined. nc, measured, but no change. Parameters are given relative to WT in each study. For I?, yes means currents are detectable. Time constants are ratios of mutant/WT. The ΔVthreshold value is the change in absolute position of the gH–V relationship versus WT. The ΔpH slope is the slope in millivolts of the relationship between Vthreshold (or other parameters reflecting the absolute position of the gH–V relationship) and Vrev or EH (which are not identical; see section Table entries defined). When C-terminal truncations are indicated as XNNNstop, this means STOP replaces X at position NNN; hence, position NNN and all subsequent residues are truncated, and the last position remaining is NNN-1. The mouse N-terminal deletions were done by replacing P78M to initiate translation at that position. Note that a large number of mutations to the linker between S4 and the C terminus have been studied (Fujiwara et al., 2012, 2014), but their results are beyond the scope of this table and thus are not included.