Fig. 5.

VU0285683 interacts with the MPEP binding site. A, 5MPEP is a neutral antagonist of VU0285683. mGluR5-expressing HEK293 cells were preincubated with 5MPEP (10 μM, ▴) or vehicle (■) for 30 min; varying concentrations of VU0285683 were added, followed by an EC₈₀ concentration of glutamate 90 s later, and the response was measured via calcium mobilization. 5MPEP shifted the VU0285683 concentration-response curve 11.8 ± 0.9-fold. B, a single point mutation that abolishes [³H]methoxyPEPy binding also blocks VU0285683-induced antagonism of mGluR5-mediated calcium mobilization in transiently transfected HEK293 cells. Introduction of A809V mutation shifted the concentration-response curve of VU0285683 5.6 ± 0.1-fold (▴) compared with wild-type mGluR5 (■). Data represent the mean ± S.E.M. of three independent experiments performed in triplicate. Data are plotted as a percentage of the EC₈₀ response to glutamate.