Figure 3.

Characterization of D79N α_2AAR-binding in mouse brain. (A–C) Competition of varying agonists for [³H]RX821002 antagonist binding (8, 11) was evaluated in the absence (open symbols) or presence (closed symbols) of 100 mM Na⁺. Total specific binding for each condition was defined as 100%; n = 3. The affinity of [³H]RX821002 was indistinguishable in WT and mutant mice (K_d = 2.3 nM in both preparations). For these and Gpp(NH)p experiments (D), 1 μM prazosin was included in incubations to block contributions from α_2BAR and α_2CAR. NMDG, N-methyl-d-glucamine. (D) Specific binding of the agonist p-[¹²⁵I]iodoclonidine was evaluated in the absence and presence of 100 μM Gpp(NH)p. Notice that the binding to D79N α_2AAR is minimal even in the absence of Gpp(NH)p. Gpp(NH)p, 5′-guanylyl β,γ-imidodiphosphate.