8hj2 | pdb_00008hj2
GPR21 wt with G15 complex
Structural highlights
FunctionGBB1_HUMAN Guanine nucleotide-binding proteins (G proteins) are involved as a modulator or transducer in various transmembrane signaling systems. The beta and gamma chains are required for the GTPase activity, for replacement of GDP by GTP, and for G protein-effector interaction.[1] Publication Abstract from PubMedGPR21 is a class-A orphan G protein-coupled receptor (GPCR) and a potential therapeutic target for type 2 diabetes and other metabolic disorders. This receptor shows high basal activity in coupling to multiple G proteins in the absence of any known endogenous agonist or synthetic ligand. Here, we present the structures of ligand-free human GPR21 bound to heterotrimeric miniGs and miniG15 proteins, respectively. We identified an agonist-like motif in extracellular loop 2 (ECL2) that occupies the orthosteric pocket and promotes receptor activation. A side pocket that may be employed as a new ligand binding site was also uncovered. Remarkably, G protein binding is accommodated by a flexible cytoplasmic portion of transmembrane helix 6 (TM6) which adopts little or undetectable outward movement. These findings will enable the design of modulators for GPR21 for understanding its signal transduction and exploring opportunity for deorphanization. Cryo-EM structures of orphan GPR21 signaling complexes.,Lin X, Chen B, Wu Y, Han Y, Qi A, Wang J, Yang Z, Wei X, Zhao T, Wu L, Xie X, Sun J, Zheng J, Zhao S, Xu F Nat Commun. 2023 Jan 13;14(1):216. doi: 10.1038/s41467-023-35882-w. PMID:36639690[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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