NMR analysis of rhodopsin–transducin interactions

Heterotrimeric G-protein activation by an agonist-stimulated G-protein coupled receptor (R ∗) requires the propagation of structural signals from the receptor interacting surfaces to the guanine nucleotide-binding pocket. Employing high-resolution NMR methods, we are probing heterotrimer-associated and rhodopsin-stimulated changes in an isotope-labeled G-protein α-subunit (G α). A key aspect of the work involves the trapping and interrogation of discrete R ∗-bound conformations of G α. Our results demonstrate that functionally important changes in G α structure and dynamics can be detected and characterized by NMR, enabling the generation of robust models for the global and local structural changes accompanying signal transfer from R ∗ to the G-protein.