Fig. 7. Kir/Gem downregulates Ca²⁺ channel activity. (A) PC12 cells were cotransfected with a GFP plasmid and cDNAs for wt or mutated Kir/Gem, either with or without 14-3-3 or 14-3-3 K49E. GFP-positive cells were selected for electrophysiology and the average of the maximal current detected at +20 mV for endogenous Ca²⁺ channels was measured. Between 9 and 16 independent experiments were carried out for each condition. (B) An example of the I-V relationship of Ca²⁺ channels in PC-12. A, Ampere; F, Faraday. Cells transfected only with the GFP cDNA served as a control.