Figure 5
CaV1.2e21+22 channels produce dominant-negative effects on L-type CaV1.2 channels, but not on T-type CaV3.1 channels.
CaV1.2e21+22 channels were co-transfected at a ratio of 1:1 with HA-CaV1.2e22, CaV3.1 or chimeric CaV3.1GCGGG channels containing CaV1.2 I-II loop in HEK293 cells with or without MG132 treatment. As control, CaV1.2e21+22 channels were replaced with pcDNA3 vectors for co-transfection. I-V curves were obtained in an external solution containing 1.8 mM Ca2+. For western blot assays, cells were biotinylated for surface proteins 36 hrs after transfection and then lysed for analysis. (A–C) Effects of CaV1.2e21+22 channels on the current density of wild-type CaV1.2e22 channels (Vector, n = 19; e21 + 22, n = 18), CaV3.1 channels (Vector, n = 9; e21 + 22, n = 11) or the chimeric CaV3.1-GCGGG channels (Vector, n = 10; e21 + 22, n = 9). *p < 0.05, #p < 0.01. (D–I) Effects of CaV1.2e21+22 channels on the surface and total expression levels of HA-CaV1.2e22 channels (D,E), CaV3.1 channels (F,G) or chimeric CaV3.1GCGGG channels (H,I, n = 3). Transferrin receptor (TfR) was used as surface protein loading control. e22, wild-type HA-CaV1.2e22 channel. e21 + 22, aberrant CaV1.2e21+22 channel. Data were shown as mean ± SEM, ns, non-significant, *p < 0.05, #p < 0.01, 1-way ANOVA with post hoc Bonferroni’s test was performed for multiple comparisons.
