Table 1. Cys-accessibility of KvAPΔ36 mutants in PE/PG versus in DOTAP.
| Mutation (which helix) | Accessibility in PE/PG | Accessibility in DOTAP | Equivalent sites in the Shaker channel | Voltage-gated activity in bilayer |
|---|---|---|---|---|
| V39C(S1) | ++ | ++ | I241 | + |
| L105C(S3b) | + | ++ | A328 | + |
| G108C(S3b) | + | + | V331 | + |
| R117C(S4) | + | − | R362 | + |
| R120C(S4) | + | + | R365 | + |
| L121C (S4) | + | + | L366 | + |
| L122C(S4) | + | + | V367 | + |
| F124C(S4) | + | − | V369 | + |
| L125C(S4) |
− |
+ |
F370 |
+ |
+, positive; ++, highly positive; −, negative.
During the reconstitution of the channel and its mutants, random insertion made the cys-accessibility assay using MTS-PEG5k only able to detect those sites that were accessible from either side of the membranes, but not able to distinguish the sidedness of the accessibility.