- Kang Y, Kuybeda O, de Waal PW, Mukherjee S, Van Eps N, Dutka P, Zhou XE, Bartesaghi A, Erramilli S, Morizumi T, Gu X, Yin Y, Liu P, Jiang Y, Meng X, Zhao G, Melcher K, Ernst OP, Kossiakoff AA, Subramaniam S, Xu HE
- Cryo-EM structure of human rhodopsin bound to an inhibitory G protein.
- Nature. 2018 Jun;558(7711):553-558. doi: 10.1038/s41586-018-0215-y. Epub 2018 Jun, 13.
- G-protein-coupled receptors comprise the largest family of mammalian transmembrane receptors. They mediate numerous cellular pathways by coupling with downstream signalling transducers, including the hetrotrimeric G proteins Gs (stimulatory) and Gi (inhibitory) and several arrestin proteins. The structural mechanisms that define how G-protein-coupled receptors selectively couple to a specific type of G protein or arrestin remain unknown. Here, using cryo-electron microscopy, we show that the major interactions between activated rhodopsin and Gi are mediated by the C-terminal helix of the Gi alpha-subunit, which is wedged into the cytoplasmic cavity of the transmembrane helix bundle and directly contacts the amino terminus of helix 8 of rhodopsin. Structural comparisons of inactive, Gi-bound and arrestin-bound forms of rhodopsin with inactive and Gs-bound forms of the beta2-adrenergic receptor provide a foundation to understand the unique structural signatures that are associated with the recognition of Gs, Gi and arrestin by activated G-protein-coupled receptors.