Table 1.
Epitope-tagged and wild-type channel selectivity
| CCD-IRK3 type | γ, pS | Po | PK/PNa | Barium block, % inhibition |
| Wild type | 14 ± 2 | 0.81 ± 0.12 | 9.5 ± 6.0 | 86 ± 2 |
| VSV tagged | 14 ± 2 | 0.88 ± 0.23 | 12.1 ± 1.3 | 86 ± 1 |
| AU1 tagged | 11 ± 4 | ND | 9.4 ± 1.8 | 92 ± 3 |
γ, the single channel conductance was measured from the inward slope conductance in cell-attached patches (n = 3 of each). Po, the open probability was near unity for the wild-type and VSV-tagged channels. Because the AU1-tagged channel appeared to exhibit similar high open probability kinetics, it was not quantified. The K-selectivity over Na PK/PNa was determined by the shift in the biionic reversal potential upon replacing 5 mM K with 5 mM Na in intact oocytes (n = 4 for each). Barium block was accessed by macroscopic analysis at −150 mV with 300 μM barium acetate in a 5 mM K bath. ND, not determined.