TABLE 1.

[³H]Ketanserin binding displacement curves by DOI in HEK293 cells co-transfected with 5-HT_2A and mGlu2/mGlu3 chimeras

DOI displacement of [³H]ketanserin (4.0 nm; K_D = 7.1 nm) binding was performed in HEK293 cells co-transfected with 5-HT_2A and mGlu2/mGlu3 chimeras. Competition curves were analyzed by nonlinear regression to derive dissociation constants for high (K_i-high) and low (K_i-low) affinity states of the receptor. % high refers to the percentage of high affinity binding sites as calculated from nonlinear fitting. Values are best fit ± S.E. of three experiments performed in duplicate. One- or two-site model as a better description of the data was determined by F test. Two-site model, p < 0.05. NA, two-site model not applicable, p > 0.05.

mGlu receptor	Ki-high (log m)	Ki-low (log m)	% High
Mock	−7.78 ± 0.4	−5.72 ± 0.2	31.2 ± 8.1
mGlu2	NA	−6.19 ± 0.2	NA
mGlu3	−7.25 ± 0.2	−3.83 ± 0.3	41 ± 8.5
mGlu2Δ TM4N	−7.21 ± 0.2	−4.92 ± 0.3	56.5 ± 6.4
mGlu2Δ TM4C	NA	−6.25 ± 0.1	NA
mGlu2-A4.40S-A4.44F	−7.97 ± 0.1	−5.01 ± 0.4	63.9 ± 11
mGlu2-A4.40S-A4.48G	−8.56 ± 0.4	−6.20 ± 0.2	33.6 ± 8.0
mGlu2-A4.44F-A4.48G	−8.68 ± 0.6	−6.56 ± 0.1	26.4 ± 7.4