Fig. 1
From: CaVβ-subunit dependence of forward and reverse trafficking of CaV1.2 calcium channels
Effect of CaVβ subunits on CaV1.2 cell surface expression in tsA-201 cells. a Schematic of CaV1.2 channel tagged with bungarotoxin binding site (CaV1.2-BBS, BBS: red triangle) between S5 and the P-loop of domain II (DII). b Representative whole-cell current traces recorded in response to depolarizing steps from − 50 to + 40 mV from a holding potential of − 100 mV from tsA-201 cells expressing either CaV1.2 WT (top traces) or CaV1.2-BBS (bottom traces) together with auxiliary subunits CaVα2δ-1 and CaVβ1b. Mean I/V curves (right panel) for CaV1.2 WT (filled circle, n = 9) and CaV1.2-BBS (open circle, n = 18) co-expressed with auxiliary subunits CaVα2δ-1 and CaVβ1b. c Confocal images showing plasma membrane expression of CaV1.2-BBS in tsA cells stained with α-bungarotoxin (BTX)-AF488 (top panels). CaV1.2-BBS was co-expressed with CaVα2δ-1 (left, no β) and either CaVβ1b (center) or CaVβ2a (right). Cells were incubated at 17 °C with BTX-AF488 for 30 min and fixed. The cells were then permeabilized and stained with a rabbit anti-CaV1.2 Ab and secondary Ab anti-rabbit AF594 (bottom panels). Scale 20 µm. d Average CaV1.2-BBS surface expression co-transfected with CaVα2δ-1 and either CaVβ1b (black bar), or CaVβ2a (open bar), or empty vector (gray bar). Bars are mean (± SEM) normalized to CaVβ1b mean. ***p < 0.001, n = 14; $$$p < 0.001, n = 5; paired t-test, n numbers correspond to independent experiments