Funding Organization(s): National Institutes of Health/National Institute of Diabetes and Digestive and Kidney Disease (NIH/NIDDK), American Asthma Foundation, Jay and Betty Van Andel Foundation, Ministry of Science and Technology (MoST, China)
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 G s (stimulatory) and G i (inhibitory) and several arrestin proteins ...
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 G s (stimulatory) and G i (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 G i are mediated by the C-terminal helix of the G i α-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, G i -bound and arrestin-bound forms of rhodopsin with inactive and G s -bound forms of the β 2 -adrenergic receptor provide a foundation to understand the unique structural signatures that are associated with the recognition of G s , G i and arrestin by activated G-protein-coupled receptors.
Organizational Affiliation:
Key Laboratory of Receptor Research, VARI-SIMM Center, Center for Structure and Function of Drug Targets, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China. eric.xu@vai.org.
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