Fig 3. A unique G protein biased mutant demonstrates agonist texture.

(A) Dopamine (DA) and quinpirole equivalently inhibit cAMP production, which is equivalent to ^[WT]D₂R for ^[Gprot4PM]D₂R (T69F Y133L Y209N A372S). (B) ^[Gprot4PM]D₂R has roughly 50% efficacy in response to DA but not quinpirole for β-arrestin 2 recruitment. (C) GRK2 overexpression rescues both DA and quinpirole β-arrestin 2 recruitment activity nearly to ^[WT]D₂R levels (dotted line, from Fig 1B). (D) GRK2 recruitment as determined by BRET (where GRK2 is tagged with YFP) shows the same ligand discrepancy as β-arrestin 2. All data are presented with SEM from n = 3 independent experiments, with statistical significance calculated in S3 Table.