FIGURE 4.

PP2A-Pep prevents constitutive internalization of GABA_B receptors and normalizes glutamate-induced loss of cell surface receptors. Neurons were transfected with GABA_B2 tagged with the binding site for α-bungarotoxin [GABA_B2(BBS)] along with EGFP for quick identification of transfected neurons and with wild type GABA_B1. After labeling cell surface receptors containing GABA_B2(BBS) with AlexaFluor 555 conjugated α-bungarotoxin at 4°C, neurons were analyzed at room temperature by life cell imaging for internalization of labeled receptors at the indicated time points and treatments. (A) Representative images (scale bar: 10 μm). (B) Quantification of the immunofluorescence signal. (C) Statistical evaluation of data 10 min after initiation of internalization. The data represent the mean ± SD of 4–7 neurons derived from three independent experiments. Two-way ANOVA followed by Tukey’s multiple comparison test (ns, p > 0.05, ****p < 0.0001).