Figure 6. The SCA27 FGF14 mutant reduces granule Ca²⁺ currents.

A. Example Ca²⁺ current traces (using Ba²⁺ as the charge carrier) recorded from a cerebellar granule cell transfected with GFP-control (black), FGF14^WT (red), or FGF14b^F150S (green). The currents were evoked by a ramp protocol from a holding potential of −80 mV to 50 mV in 1 sec. B. Summary data from granule cells expressing GFP control (n=17), FGF14^WT (n=25), or FGF14b^F150S (n=16). C. Example Ca²⁺ channel current traces recorded from a cerebellar granule cell transfected with GFP-control (black), FGF14^WT (red), or FGF14b^F150S (green). The currents were evoked by a step protocol from a holding potential of −80 mV to −10 mV in 500 ms. D. Summary data from granule cells expressing GFP control (n=22), FGF14^WT (n=37), or FGF14b^F150S (n=13). E. Representative Cd²⁺-sensitive Ba²⁺ currents evoked by a single action potential waveform (APW, top) command recorded from granule cells transfected with GFP control (black), scrambled control shRNA (gray), or FGF14 shRNA (blue). The integrated current (Q) is colored with black, red, or green. F. Summary data of the integrated current (Q) normalized to each cell capacitance. Summary results were obtained from granule cells expressing GFP control (n=25), FGF14^WT (n=28), or FGF14b^F150S (n=16). **p<0.01 versus Control.