Fig. 2.

Quantitative assessment of BTX binding to GABA_AR β3-expressing HEK 293 cells. (a) BTX binding to a stably transfected cell line was measured by quantitative fluorescence microscopy (10). (Inset) Double-reciprocal plot shows that K_d ≈ 50 nM. (b) BTX binding to this cell line was insensitive to preincubation with blockers of nAChRs containing α1 or α7 subunits [methyllycaconitine (MLA), nicotine (Nic), and hexamethonium (Hexa)] or the GABA_ΑR modulator pentobarbital (PB) but was blocked by the GABA_ΑR antagonist bicuculline (Bic).