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 (Gα). A key aspect of the work involves the trapping and interrogation of discrete R∗-bound conformations of Gα. Our results demonstrate that functionally important changes in Gα 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.