TABLE 4

Expression levels (±S.E.M.) of the D2L receptor are unaffected by expression of various G proteins

Flp-In-T-REx HEK293 cells were established able to express pertussis toxin-resistant forms of each of Gαi1, Gαi2, Gαi3, and Gαo1 in a tetracycline-dependent fashion (see Fig. 4 for details). These cells were further transfected to express the D2L receptor stably and constitutively. Individual clones were subsequently isolated. After pertussis toxin treatment and treatment with or without 1 μg/ml tetracycline, saturation [3H]spiperone ligand binding studies were performed on membrane preparation as detailed under Materials and Methods. Data represent means ± S.E.M. of both Bmax and Kd values from at least three experiments performed on different membrane preparations. Induction of G protein expression did not significantly alter D2L receptor expression levels.


Cell Line

[3H]Spiperone Binding
- 1 μg/ml Tetracycline
+ 1 μg/ml Tetracycline
Bmax
Kd
Bmax
Kd
fmol/mg nM fmol/mg nM
D2L + Gαi1 988 (108) 0.02 (0.01) 1156 (261) 0.03 (0.01)
D2L + Gαi2 1448 (191) 0.02 (0.01) 1861 (225) 0.04 (0.01)
D2L + Gαi3 538 (52) 0.03 (0.01) 510 (120) 0.02 (0.02)
D2L + Gαo1
3790 (396)
0.06 (0.02)
3864 (249)
0.07 (0.02)