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Photocleavage of the polypeptide backbone is potentially a powerful and general method to activate or deactivate functional peptides and proteins with high spatial and temporal resolution. Here we show that 2-nitrophenylalanine is able to photochemically cleave the polypeptide backbone by an unusual cinnoline-forming reaction. This unnatural amino acid was genetically encoded in E. coli, and protein containing 2-nitrophenylalanine was expressed and site-specifically photocleaved.

The G‐protein‐coupled human cannabinoid receptor 1 (CB1) is a promising therapeutic target for pain management, inflammation, obesity, and substance abuse disorders. The structures of CB1‐Gi complexes in synthetic agonist‐bound forms have been resolved to date. However, the commercial drug recognition and Gq coupling mechanisms of CB1 remain elusive. Herein, the cryo‐electron microscopy (cryo‐EM) structure of CB1‐Gq complex, in fenofibrate‐bound form, at near‐atomic resolution, is reported. The structure elucidates the delicate mechanisms of the precise fenofibrate recognition and Gq protein coupling by CB1 and will facilitate future drug discovery and design. [ABSTRACT FROM AUTHOR]