Quantifying the Absolute Number of Voltage Gated EGFP Tagged Ion Channels by Fluorescence Intensity Measurements

Abstract

In the past, much work has been done to evaluate the gating charge, q, of single voltage gated K+ or Na+ channels. A figure of about 13 e is generally accepted for K+ channels. For Na+ channels, the figure of q estimated by various methods, is less well established and ranges from 5 to 15 e. Recently, we determined the gating charge of single Na+ channels indirectly to be about 6 e by applying our newly determined ratio of q K+ /q Na+ = 2.5±0.4 (Gamal El-Din et al. 2008) and assuming 13 e for q K+.