Figure 2.

Spontaneous activity of human AChR in saline and in serum. (Left) Example currents recorded in serum, without the addition of agonist to the patch solution. (Right) The mean patch open probability (2–10 patches) for wild-type and SCCMS AChRs exposed to saline (filled bars) or to human serum (open bars). SCCMS AChR have a higher open probability in saline and are more strongly activated by serum than the wild type (note the logarithmic scale). The vertical white lines in ɛT264P and αS269I indicate the patch open probabilities in serum that was pretreated with choline oxidase. The reduction in spontaneous activity after choline oxidase treatment indicates that the component of serum that activates the mutant AChR is choline. The calibration of time is 50 ms except for αV249F, which is 750 ms.