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From Proteopedia
Cryo-EM structure of pseudoallergen receptor MRGPRX2 complex with PAMP-12, state2
Structural highlights
FunctionMRGX2_HUMAN Mast cell-specific receptor for basic secretagogues, i.e. cationic amphiphilic drugs, as well as endo- or exogenous peptides, consisting of a basic head group and a hydrophobic core (PubMed:25517090). Recognizes and binds small molecules containing a cyclized tetrahydroisoquinoline (THIQ), such as non-steroidal neuromuscular blocking drugs (NMBDs), including tubocurarine and atracurium. In response to these compounds, mediates pseudo-allergic reactions characterized by histamine release, inflammation and airway contraction (By similarity). Acts as a receptor for a number of other ligands, including peptides and alkaloids, such as cortistatin-14, proadrenomedullin N-terminal peptides PAMP-12 and, at lower extent, PAMP-20, antibacterial protein LL-37, PMX-53 peptide, beta-defensins, and complanadine A.[UniProtKB:Q3KNA1][1] [2] [3] [4] [5] [6] [7] Publication Abstract from PubMedIn the clades of animals that diverged from the bony fish, a group of Mas-related G-protein-coupled receptors (MRGPRs) evolved that have an active role in itch and allergic signals(1,2). As an MRGPR, MRGPRX2 is known to sense basic secretagogues (agents that promote secretion) and is involved in itch signals and eliciting pseudoallergic reactions(3-6). MRGPRX2 has been targeted by drug development efforts to prevent the side effects induced by certain drugs or to treat allergic diseases. Here we report a set of cryo-electron microscopy structures of the MRGPRX2-Gi1 trimer in complex with polycationic compound 48/80 or with inflammatory peptides. The structures of the MRGPRX2-Gi1 complex exhibited shallow, solvent-exposed ligand-binding pockets. We identified key common structural features of MRGPRX2 and describe a consensus motif for peptidic allergens. Beneath the ligand-binding pocket, the unusual kink formation at transmembrane domain 6 (TM6) and the replacement of the general toggle switch from Trp(6.48) to Gly(6.48) (superscript annotations as per Ballesteros-Weinstein nomenclature) suggest a distinct activation process. We characterized the interfaces of MRGPRX2 and the Gi trimer, and mapped the residues associated with key single-nucleotide polymorphisms on both the ligand and G-protein interfaces of MRGPRX2. Collectively, our results provide a structural basis for the sensing of cationic allergens by MRGPRX2, potentially facilitating the rational design of therapies to prevent unwanted pseudoallergic reactions. Structure, function and pharmacology of human itch receptor complexes.,Yang F, Guo L, Li Y, Wang G, Wang J, Zhang C, Fang GX, Chen X, Liu L, Yan X, Liu Q, Qu C, Xu Y, Xiao P, Zhu Z, Li Z, Zhou J, Yu X, Gao N, Sun JP Nature. 2021 Dec;600(7887):164-169. doi: 10.1038/s41586-021-04077-y. Epub 2021, Nov 17. PMID:34789875[8] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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