Posts Tagged ‘receptor’

Pharyngeal stimulation with sugar triggers local searching behavior in Drosophila [RESEARCH ARTICLE]

Satoshi Murata, Axel Brockmann, and Teiichi Tanimura
Foraging behavior is essential for all organisms to find food containing nutritional chemicals. A hungry Drosophila melanogaster fly performs local searching behavior after drinking a small amount o…

Phase-plate cryo-EM structure of a class B GPCR–G-protein complex

Class B G-protein-coupled receptors are major targets for the treatment of chronic diseases, such as osteoporosis, diabetes and obesity. Here we report the structure of a full-length class B receptor, the calcitonin receptor, in complex with peptide ligand and heterotrimeric Gαsβγ protein determined by Volta phase-plate single-particle cryo-electron microscopy. The peptide agonist engages the receptor by binding to an extended hydrophobic pocket facilitated by the large outward movement of the extracellular ends of transmembrane helices 6 and 7. This conformation is accompanied by a 60° kink in helix 6 and a large outward movement of the intracellular end of this helix, opening the bundle to accommodate interactions with the α5-helix of Gαs. Also observed is an extended intracellular helix 8 that contributes to both receptor stability and functional G-protein coupling via an interaction with the Gβ subunit. This structure provides a new framework for understanding G-protein-coupled receptor function.

High-resolution crystal structure of the human CB1 cannabinoid receptor

The human cannabinoid G-protein-coupled receptors (GPCRs) CB1 and CB2 mediate the functional responses to the endocannabinoids anandamide and 2-arachidonyl glycerol (2-AG), as well as the widely consumed plant (phyto)cannabinoid Δ9-tetrahydrocannabinol (THC)1. The cannabinoid receptors have been the targets of intensive drug discovery efforts owing to the therapeutic potential of modulators for controlling pain2, epilepsy3, obesity4, and other maladies. Although much progress has recently been made in understanding the biophysical properties of GPCRs, investigations of the molecular mechanisms of the cannabinoids and their receptors have lacked high-resolution structural data. We used GPCR engineering and lipidic cubic phase (LCP) crystallization to determine the structure of the human CB1 receptor bound to the inhibitor taranabant at 2.6 Å resolution. The extracellular surface of CB1, including the highly conserved membrane-proximal amino-terminal (N-terminal) region, is distinct from other lipid-activated GPCRs and forms a critical part of the ligand binding pocket. Docking studies further demonstrate how this same pocket may accommodate the cannabinoid agonist THC. Our CB1 structure provides an atomic framework for studying cannabinoid receptor function, and will aid the design and optimization of cannabinoid system modulators for therapeutic ends.

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