Figure 4
Binding characteristics of the partial agonist taurine to α1-GFP GlyR nanodiscs. (a) Dose–response data for glycine and taurine of heterologous expressed α1 GlyR from X. laevis oocytes. Taurine acts as a partial agonist with an aEC50 value of 843 ± 16 µM reaching a maximum current of 61% compared to glycine (n = 3). Taurine currents are normalized to the maximum glycine currents for each cell. Dose–response data of glycine are the same as shown in Fig. 3. Error bars represent SEM. (b) MST binding experiment of α1-GFP GlyR with a taurine titration series of 6 µM to 12.5 mM results in a cEC50 value of 473.8 ± 46.1 µM (n = 3). Error bars represent SEM. (c) Exemplary α1-GFP GlyR MST data of taurine (blue circles) and glycine (black circles) obtained from oocytes displaying a difference in their maximal thermophoretic mobility (grey and blue arrows). (d) Comparison of the signal amplitudes of α1-GFP GlyR SMALPs expressed in HEK293 cells and oocytes for glycine and taurine. Binding of taurine leads to a significant decreased thermophoretic movement (p = 0.024, unpaired two-side t test, n = 3) with signal amplitudes of 1.32 ± 0.14 compared to glycine-bound receptors with signal amplitudes of 3.38 ± 1.09. Data are shown in mean ± SD.
