Table 1.
Effects of aphid selectivity filter residue changes to D. melanogaster DmNav1 channels expressed in Xenopus oocytes: DENA and DENS mutants impart TTX-insensitivity and alter channel activity.
| Selectivity filter Motifs |
||||
|---|---|---|---|---|
| DEKA | DEKS | DENA | DENS | |
| Vrev (mV) | 71.4 ± 2.7 | 83.9 ± 4.2∗∗ | 18.6 ± 0.6∗∗∗ | 23.9 ± 0.7∗∗∗ |
| V50,act (mV) | −17.6 ± 0.5 (16) | −14.3 ± 0.5 (12) | −12.6 ± 3.0 (8)∗ | −23.4 ± 0.7 (8) |
| kact (mV) | 8.0 ± 0.5 | 9.6 ± 0.5 | 12.8 ± 2.2 | 6.1 ± 0.6 |
| V50,inact (mV) | −47.0 ± 0.3 (16) | −47.1 ± 0.6 (12) | −41.1 ± 1.5 (8)∗∗∗ | −41.8 ± 0.5 (8)∗∗∗ |
| kinact (mV) | 5.4 ± 0.3 | 5.2 ± 0.5 | 9.4 ± 1.2 | 7.4 ± 0.5 |
| τdecay – 10 mV (ms) | 1.3 ± 0.03 (16) | 1.4 ± 0.02 (12)∗∗ | 1.9 ± 0.1 (8)∗∗∗ | 1.8 ± 0.05 (8)∗∗∗ |
| TTX IC50 | 8.7 ± 1.2 nM (7) | 3.2 ± 0.6 nM (10)∗∗∗ | 335 ± 47 nM (4)∗∗∗ | 2393 ± 262 nM (11)∗∗∗ |
| Size of current (at −10 mV) | >1 μA | >1 μA | >1 μA | >1 μA |
| Tail currents present | No | No | Yes | Yes |
Statistical comparisons were made between the DEKA channel and the three pore variants using one-way ANOVA with Dunnett’s post-test. IC50 values were compared using an Extra Sum of Squares F test. Probability (P) values are ∗P < 0.05; ∗∗P < 0.01; ∗∗∗P < 0.001. Numbers in parentheses indicate the number of oocytes tested.