Fig. 5
Persistent Gi/o protein-GIRK coupling throughout the activation cycle. a (Left) Schematic representation of colocalizing GIRK and Gi/o proteins in the activation cycle. (Right) Ribbon diagrams of a representative structure of the Gαi3βγ–GIRK complex in the ensemble model and the model structure of the Gαi3(GTP)–GIRK–Gβγ complex, using the crystal structures of the GIRK chimera (PDB ID: 2QKS_1)27, Gαi1βγ (PDB ID: 1GP2)33, Gαi1(GTP) (PDB ID: 1GIA)63, and Gβγ (from PDB ID: 4KFM)42. The model of the Gαi3(GTP)–GIRK–Gβγ complex was built by integrating the model of the Gαi3(GTP)–GIRK complex21 with the crystal structure of the GIRK–Gβγ complex42. b Components of the complex in the inactive (top) and active (bottom) states are shown as surfaces. Residues on the Gαi3βγ–GIRK binding interface (residues within 5.5 Å distance) are colored green. Residues on the Gαi3(GTP)–GIRK binding surfaces identified by transferred cross-saturation experiments21, and the Gβγ–GIRK binding surfaces42,43 are colored red and blue, respectively. GD GTPase domain, HD helical domain
