FIGURE 2.

Screening for a peptide (R2-Pep) interfering with the interaction of CHOP with GABA_B receptors. (A) Scheme of the C-terminal domain of GABA_B2 with the coiled-coil domain (orange box), which contributes to the CHOP-GABA_B receptor interaction site and location of the interfering peptide R2-Pep sequence (red box). The box below depicts the GABA_B2 peptide sequences used for screening. (B) Peptide 5 reliably prevented stress-induced decrease in GABA_B1/GABA_B2 heteromers. Cultures were stressed for 2 h with thapsigargin (1 μM) and immediately thereafter treated for 30 min with the peptides indicated in (A). Neurons were then tested for the interaction between GABA_B1 and GABA_B2 by in situ PLA. The in situ PLA signals of the untreated neurons served as control (-, no peptide). The data represent the mean ± S.E.M. of 8–40 neurons derived from two independent experiments (control, n = 4). ns, p > 0.05; *, p < 0.05; **, p < 0.005; ***; p < 0.0005. Brown-Forsythe/Welch one-way ANOVA followed by Games-Howell’s multiple comparison test. (C) R2-Pep (peptide 5 in B) interacted with CHOP. Cultures were stressed for 2 h with thapsigargin (1 μM) and immediately thereafter treated with R2-Pep for 30 min. Neurons were then tested for the interaction of CHOP with R2-Pep by in situ PLA using antibodies directed against CHOP and FITC (R2-Pep was labeled with FITC at the N-terminus). The data represent the mean ± S.E.M. of 47–62 neurons derived from two independent experiments. ns, p > 0.05; ****; p < 0.0001. Kruskal–Wallis test followed by Dunn’s multiple comparison test.