TABLE 1

EC₅₀ and I_max values of the GABA-induced currents for all mutants

Note that although we injected similar amount of RNA for all constructs, the expression levels were not strictly controlled because of batch-to-batch variability of oocytes and testing date after injection. Thus, I_max cannot be used to estimate the influence of gating on EC₅₀. Because most mutants have the I_max values that were not dramatically reduced, the contribution of gating influence on EC₅₀ are relatively small in these mutants. However, we noted that Y106S+F138Y+V140L+FYS240VF and Y102F+V106S+F138Y+V140L+FYS240VF ρ1 mutants have relatively low expression. This is further confirmed by comparison of their expression levels to the wild-type receptor in the same batch of oocytes and in the same time period after injection. The results showed that the I_max values for Y106S+F138Y+V140L+FYS240VF and Y102F+Y106S+F138Y+V140L+FYS240VF were 13 and 15% of the wild type expression level respectively.