Table 2.
Properties of KCNQ2 mutant channels
| KCNQ2 mutants | Interaction with CaM | KCNQ2/3 activity | Coassembly with KCNQ3 | Membrane localization |
|---|---|---|---|---|
| R345E | − | −(2/30) | + | + |
| I340E | − | −(0/21) | + | + |
| M566T/D567Y | + | +(15/17) | + | + |
| ΔDVMD | + | +(12/17) | + | + |
| A4 | + | +(4/4) | + | + |
| K555E/K557E | + | +(17/21) | + | + |
| K553E/R554E | − | −(2/27) | + | + |
| K553E | + | +(5/5) | + | + |
| R554E | + | +(6/6) | + | + |
Interaction with CaM and coassembly with KCNQ3 were assayed by coimmunoprecipitation. Membrane localization was assayed by surface biotinylation. KCNQ2/3 activity was measured from CHO cells cotransfected with the KCNQ2 mutants and KCNQ3 subunit cloned into the bicistronic pIRES vector. Numbers of cells that gave measurable currents, n, of the total numbers of cells recorded,N, are shown in parentheses (n/N). With wild-type KCNQ2, 130 of 130 cells exhibited currents. For all assays the positive results are indicated by a plus sign without specifying any quantitative differences between mutants. R345E and I340E are mutated in the CaM binding site 1, whereas the rest have mutations in site 2. A4 represents K553A/R554A/K555A/K557A. ΔDVMD has a 4-amino-acid deletion from D564 to D567.