{"type": "root", "children": [{"type": "p", "children": [{"type": "t", "text": "\nMRGPRX2 is a mast cell–specific G protein–coupled receptor (GPCR) that recognizes a wide array of basic, cationic ligands. Several studies have demonstrated that this receptor binds neuropeptides such as cortistatin and substance P, as well as host defense peptides like LL-37 and human β-defensins, thereby triggering mast cell activation in a non–IgE-mediated manner. In patients with chronic urticaria, for instance, increased responsiveness to neuropeptides has been linked to MRGPRX2 activation, highlighting its role in eliciting larger and more prolonged wheal responses."}, {"type": "fg", "children": [{"type": "fg_fs", "start_ref": "1", "end_ref": "4"}]}, {"type": "t", "text": "\n"}]}, {"type": "t", "text": "\n\n"}, {"type": "p", "children": [{"type": "t", "text": "\nUpon activation, MRGPRX2 initiates intracellular signaling cascades involving both Gαq and Gαi proteins, resulting in sustained calcium mobilization and mast cell degranulation. Structural investigations using cryo–electron microscopy and mutagenesis studies have identified key transmembrane residues and intracellular domains—including a critical NPxxY motif—that govern ligand binding, receptor coupling, and internalization. Moreover, responses to various drugs used in perioperative procedures, as well as endogenous mediators in the airways, reveal that interindividual variability and specific missense variants in receptor extracellular and transmembrane regions can markedly influence MRGPRX2 function."}, {"type": "fg", "children": [{"type": "fg_fs", "start_ref": "5", "end_ref": "16"}]}, {"type": "t", "text": "\n"}]}, {"type": "t", "text": "\n\n"}, {"type": "p", "children": [{"type": "t", "text": "\nBeyond its biochemical and signaling properties, MRGPRX2 plays a key role in various physiological and pathological processes. Activators of this receptor—including angiotensin metabolites, sinomenine hydrochloride, and the protease mucunain from cowhage—contribute to neurogenic inflammation, pruritus, and pseudo–allergic drug reactions. These mechanisms underlie clinical conditions such as chronic urticaria, atopic dermatitis, and perioperative hypersensitivity reactions, thereby positioning MRGPRX2 as an attractive therapeutic target for modulating mast cell–mediated inflammation across multiple settings."}, {"type": "fg", "children": [{"type": "fg_fs", "start_ref": "17", "end_ref": "20"}]}, {"type": "t", "text": "\n"}]}, {"type": "rg", "children": [{"type": "r", "ref": 1, "children": [{"type": "t", "text": "Nicola Robas, Emma Mead, Mark Fidock "}, {"type": "b", "children": [{"type": "t", "text": "MrgX2 is a high potency cortistatin receptor expressed in dorsal root ganglion."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "J Biol Chem (2003)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1074/jbc.M302456200"}], "href": "https://doi.org/10.1074/jbc.M302456200"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "12915402"}], "href": "https://pubmed.ncbi.nlm.nih.gov/12915402"}]}, {"type": "r", "ref": 2, "children": [{"type": "t", "text": "Hariharan Subramanian, Kshitij Gupta, Qiang Guo, et al. 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