Fig. 6.
UK14,304 competition binding curves suggest enhanced coupling of α2AAR to G protein in brain preparations derived from Sp(−/−) mice. Competition binding assays were performed with brain particulate preparations derived from WT or Sp(−/−) mice in the presence or absence of Gpp(NH)p, as indicated. Binding of the [3H]rauwolscine radioligand is given as a percentage of binding without competitors. Curves without GppNHp were best fit via nonlinear regression analysis to two binding sites, whereas curves obtained in incubations performed in the presence of GppNHp were best fit by nonlinear regression analysis to one binding site (see Table 2 for estimates of Kd for each affinity state and percentage of receptors in the higher affinity state for these curves). Values represent mean ± S.E.M. n = 4 for each genotype.