Figure 5.

Gα_q coupling selectivity of the GRPr. Membranes containing GRPr (0.4 nM) were mixed with Gα_q (280 nM) and βγ (1 μM), G_i/o (1 μM), or Gα_t (1 μM) and βγ (1 μM). GTPγS exchange for bound GDP in the presence (stippled bars) or absence (solid bars) of 1 μM GRP proceeded for 15 min at 30°C as described. Gα subunit concentrations were determined by GTPγS binding with or without addition of βγ. Membrane-independent background binding of GTPγS was subtracted from total binding to give the values presented in the figure (membrane-independent backgrounds were as follows: 635 cpm for Gα_q and βγ; 716 cpm for G_i/o; and 3173 cpm for Gα_t and βγ).