FIGURE 6.

CaMDN increases the open probability but not unitary conductance of tandem-cloned channels. A and B, representative sets of single-channel traces were recorded from CHO cells expressed with either Tandem alone (black) or Tandem + CaMDN (gray) at a −70 mV step potential. The dotted lines represent closed states. Amplitude histograms of Tandem + CaMWT and Tandem + CaMDN at −70 mV were fitted with a Gaussian function to find a peak point. I, current. C, data from amplitude histograms of applied voltages were used to generate current-voltage relationships. The single-channel conductances were 13 ± 0.6 pS (n = 8) (Tandem alone) and 13 ± 0.2 (n = 7) pS (Tandem + CaMDN), respectively. D and E, the open probability data were generated from at least 200 sweeps at a specific test potential using recordings from Tandem alone and Tandem + CaMDN. Mean open probabilities are shown at the top. F, exponential fits to the first latency histograms. Time constants of Tandem alone (blue) and Tandem + CaMDN (red) are indicated in milliseconds.