Knowra Histamine H1 receptor Histamine H1 receptor The histamine H1 receptor is a G protein-coupled receptor that responds to histamine. It mediates effects including wakefulness, smooth-muscle contraction, increased vascular permeability, and allergic symptoms.
G protein-coupled receptor : A membrane receptor that activates intracellular signaling by engaging heterotrimeric G proteins. H1 belongs to this receptor family and signals primarily through Gq/11 proteins.
Allergic rhinitis : Inflammation of the nasal lining caused by an allergic response to inhaled substances. H1 signaling contributes to sneezing, itching, and nasal symptoms.
Receptor (biochemistry) : A molecule, usually a protein, that detects a signal and initiates a biological response. The H1 receptor is one specific receptor for a chemical messenger.
Histamine H2 receptor : A histamine-activated G protein-coupled receptor that chiefly stimulates gastric acid secretion through Gs signaling. H2 receptors, unlike H1 receptors, mediate much of histamine’s effect on stomach acid.
Gq alpha subunit : A heterotrimeric G-protein subunit that activates phospholipase C-beta when bound to GTP. Activated H1 receptors couple chiefly to Gq/11, initiating downstream signaling.
Urticaria : A skin condition marked by transient, itchy wheals caused by localized edema. Histamine acting at H1 receptors drives much of the wheal-and-itch response.
Ligand : A molecule that binds selectively to another molecule, such as a receptor. Histamine is the ligand whose binding changes H1 receptor activity.
Histamine H3 receptor : A presynaptic histamine receptor that commonly inhibits neurotransmitter release through Gi/o signaling. H3 often limits histamine release, whereas H1 commonly conveys excitatory responses.
Phospholipase C : An enzyme family that cleaves phospholipids to generate signaling molecules such as IP3 and diacylglycerol. Gq/11 activation recruits this enzyme to relay H1 receptor signals.
Blood-brain barrier : A selective interface that regulates movement of substances between the blood and central nervous system. Whether an H1-blocking drug crosses this barrier strongly affects sedation.
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