Extended Data Table 2.

Cryo-EM data collection, refinement, and validation statistics.

	Rho*–GRK1 (ensemble1†)	Rho*–GRK1S5E/EE (ensemble1)	Fab1 (ensemble1)	Fab6 (ensemble1)
Data collection and processing
Magnification	81,000 x	81,000 x	81,000 x	81,000 x
Voltage (kV)	300	300	300	300
Electron exposure(e-/Å2)	~54	~54	~54	~54
Defocus range (μm)	1.2 – 2.5	1.2 – 2.5	1.2 – 2.5	1.2 – 2.5
Pixel size (Å)	1.08	1.08	1.08	1.08
Symmetry imposed	C1	C1	C1	C1
Initial particle images (no.)	2,680,798	2,719,144	5,699,968	7,524,629
Final particle images (no.)	183,717	132,721	310,363	250,547
Map resolution (Å)	7.0	5.8	4.1	4.0
FSC threshold	0.143	0.143	0.143	0.143
Map resolution range (Å)	6 – 11	4.2–11	3.6–10	3.4–10
Refinement with MDFF
Initial model used(PDB entry)	Rho*: 3PQR; GRK1: a homology model of 3NYN, Fab models: SWISSMODEL68
Model composition
Non-hydrogen atoms	5358	5363	8699	8707
Residues	Protein: 670	Protein: 670	Protein:1108	Protein: 1109
Ligands	Sgv: 1 Ret: 1	Sgv: 1 Ret: 1	Sgv: 1 Ret: 1	Sgv: 1 Ret: 1
R.m.s. deviations
Bond lengths (Å)	0.019	0.019	0.143	0.019
Bond angles (°)	2.01	1.95	2.88	2.02
Validation
MolProbity score	1.31	1.26	1.22	1.17
Clash score	0.48	0.48	0.24	0.18
Poor rotamers (%)	1.52	1.52	1.46	1.46
Ramachandran Plot
Favored (%)	91.6	92.8	91.4	92.3
Allowed (%)	6.3	5.9	6.2	6.1
Disallowed (%)	2.1	1.4	2.4	1.6

^†The ensemble most similar to all other ensembles (lowest backbone RMSD over the Rho*–GRK1 complex residues) was used to generate statistics.