GABA-activated current. Nevertheless, under these conditions,
we can measure a DZP-mediated current. Figure 3
shows recordings from oocytes expressing high levels of wildtype
a1b2g2 GABAA receptors. As evident in Figure 3a, 1 mM
GABA induced a current of 3.4 mA. Figure 3a also shows the
current in response to 1 mM DZP alone. As will be shown
subsequently, this is a maximal concentration of DZP. We
also were able to observe a DZP-mediated current in oocytes
expressing a1b2Y205Sg receptors (data not shown). This
mutation in the GABA binding site imparts a 950-fold increase
in the EC50, thus negating the possibility that residual GABA