Table 6.
Effect of α‐actinin‐1 ectopic expression on biophysical properties of CaV1.2 single‐channel currents
| Gating parameter | Availability (%) | NPopen (%) | Popen (%) | I (Mean ensemble Avg.) [fA] | Unitary current (pA) | Sweeps | n |
|---|---|---|---|---|---|---|---|
| WT (a) | 56.6 ± 6.3 | 3.6 ± 0.75 | 3.4 ± 0.69 | 14.8 ± 3.1 | 0.89 ± 0.02 | 2,744 | 32–35 |
| WT + α‐Actinin (b) | 76.5 ± 6.2* | 9.2 ± 2.0** | 7.9 ± 2.0* | 31.3 ± 7.5* | 0.84 ± 0.02 | 2,388 | 23–25 |
| WT + EE847/851KK (c) | 32.9 ± 7.5**** | 1.9 ± 0.7** | 1.8 ± 0.7* | 7.4 ± 2.8* | 0.83 ± 0.03 | 1,252 | 13 |
| K1647E + α‐Actinin (d) | 43 ± 5.0 | 1.8 ± 0.3 | 1.7 ± 0.3 | 8.5 ± 1.5 | 0.83 ± 0.01 | 2,601 | 30 |
| K1647E + EE847/851KK (e) | 67.9 ± 6.9** | 2.6 ± 0.5 | 2.5 ± 0.5 | 11.3 ± 2.7 | 0.84 ± 0.02 | 1,376 | 16 |
| Unpaired t‐test | a‐b¥ | a‐b¥ | a‐b¥ | a‐b¥ | NS | ||
| b‐c¥ | b‐c¥ | b‐c¥ | b‐c¥ | ||||
| d‐e¥ | d‐e P = 0.7 | d‐e P = 0.7 |
HEK293 cells were transiently transfected with WT CaV1.2 (α11.2, α2‐δ1, and β2a) and, if indicated, with α‐actinin‐1 WT or E847K/E851K. Single‐channel activity was obtained as in Table 5. Statistical significance was determined by pairwise testing of CaV1.2 WT alone (a) versus CaV1.2 WT + α‐actinin WT (b), CaV1.2 WT + α‐actinin‐1 WT versus CaV1.2 + α‐actinin‐1 E847K/E851K (c), and CaV1.2 K1647E + α‐actinin‐1 WT (d) versus CaV1.2 K1647E + α‐actinin‐1 E847K/E851K (e) with an unpaired t‐test¥. Given are mean values ± SEM (*P < 0.05, **P < 0.01, ****P < 0.0001). Values for CaV1.2 WT are provided for comparison from Table 5.