FIGURE 6.

Mutation of S408/9 leads to the formation of α1α4-containing GABA_ARs. (A) Purified PM from S408/9A mice were exposed to non-immune control IgG or the α1 subunit antibody and probed for the α1 subunit. Major bands at 250 and 720 kDa were observed. (B) Quantitative analysis of the contents of the 250 kDa band revealed that the α4 and α5 subunits are significantly enriched in α1-containing GABA_ARs in S408/9A mice, along with the α1, α3, β1–3, γ2, and δ subunits (*p < 0.05, **p < 0.01, ***p < 0.001, ****p < 0.0001, n = 5 replicates). (C) Contribution of each α subunit variant to the total amount of α subunits is compared between α1-containing GABA_ARs from WT and S408/9A mice. With the S408/9A mutation, the percentages of the α1 and α2 subunits decrease whereas those of the α3, α4, and α5 subunits increase. (D) The α4 subunit antibody recognized a major band at 250 kDa in purified α4-containing GABA_ARs from S408/9A mice. (E) In α4-containing GABA_ARs from S408/9A mice, only the α4 and β3 subunits are significantly enriched (**p < 0.01, n = 5 replicates). (F) The S408/9A mutation does not affect the efficacy of the purification of either α1- or α4-containing GABA_ARs (ns ≥ 0.05, n = 5 replicates).