Fig. 1.

Coupling to wild-type heterotrimers in permeabilized, nucleotide-depleted cells. (A) Receptors were fused to Renilla luciferase (Rluc8), and Gβγ dimers were fused to Venus. (B) Time course of BRET between H₁R-Rluc8 and Gα_i1βγ-Venus in response to 100 μM histamine (HA) in permeabilized cells in the presence (GDP) and absence (apyrase) of nucleotides. (C and D) H₁R couples to G_s, G_i1, and G_q heterotrimers; **P = 0.0011, ****P < 0.0001, n.s. not significant; one-way ANOVA, Sidak’s multiple comparisons. Pertussis toxin S1 subunit (PTX) was coexpressed in experiments with Gα_s, Gα_q, and Gα₁₂. (E) Similar potency of histamine-induced coupling to G_i1 (EC₅₀ = 258 nM; n = 4) and G_q (EC₅₀ = 245 nM; n = 7) heterotrimers.