Figure 2: Role of the Cav1.2 auxiliary subunits. (A) Epifluorescent images of the expressing COS1 cells showing distribution of EYFPN-α 1C obtained with the YFP filter (scaling bars, 4 μm) and traces of the maximum calcium current recorded in response to 600 ms steps to +30 mV from the holding potential mV (left). (B) Relative distribution of EYFPN-α 1C in the plasma membrane (PM) over the cytoplasm in the absence (a) or presence of α 2δ (b), β 2d (c), or α 2δ + β 2d (d). The ratio of fluorescence intensity in PM over the area underneath PM was averaged after background subtraction in each cell. The ratio less than 1.0 indicates lack of significant PM targeting by α 1C. * .