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. 2009 Apr 29;587(Pt 12):2903–2918. doi: 10.1113/jphysiol.2009.170662

Figure 2. The kinetics of the Orai1/STIM1 mediated current under different transfection conditions.

Figure 2

A, dependence of the inactivation at negative potentials on the amount of the Orai1 plasmid. Each point represents the relative amplitude of the Orai1/STIM1 mediated current at the end of the 200 ms step to −118 mV (I200) normalised to the peak current at the beginning of the step (I0). Open circles represent averaged data for the 0.4 pmol of STIM1. For comparison, the averaged data for 0.1 pmol STIM1 and 0.1 pmol Orai1 is presented (filled circle). Number of cells is indicated in brackets. Note that the extent of the current inactivation in the cells transfected with 0.1 pmol STIM1 and 0.1 pmol Orai1 is not different from that in cells transfected with 0.4 pmol STIM1 and 0.4 pmol Orai1 (P= 0.6). Continuous line represents linear regression for the data obtained with the range of Orai1 concentrations and 0.4 pmol STIM1 (r2= 0.48; P < 0.0001). B, dependence of the inactivation at negative potentials on the amount of the STIM1 plasmid. Continuous line represents linear regression for the data obtained with the range of STIM1 concentrations and 0.4 pmol Orai1 (r2= 0.98; P < 0.01). C, example of the currents recorded from a cell transfected with 1 Orai1/2 (STIM1+GFP) mixture. D, example of the currents recorded from a cell transfected with 2 (Orai1+GFP)/1 STIM1 mixture. Current traces were obtained in response to 600 ms steps ranging from −138 mV to −38 mV in 20 mV increments. E, example of the currents obtained in HEK293 cells using similar transfection mixtures.