Aliases for HRH3 Gene
External Ids for HRH3 Gene
Histamine is a ubiquitous messenger molecule released from mast cells, enterochromaffin-like cells, and neurons. Its various actions are mediated by histamine receptors H1, H2, H3 and H4. This gene encodes one of the histamine receptors (H3) which belongs to the family 1 of G protein-coupled receptors. It is an integral membrane protein and can regulate neurotransmitter release. This receptor can also increase voltage-dependent calcium current in smooth muscles and innervates the blood vessels and the heart in cardiovascular system. [provided by RefSeq, Jul 2008]
GeneCards Summary for HRH3 Gene
HRH3 (Histamine Receptor H3) is a Protein Coding gene. Diseases associated with HRH3 include hepatic coma and sleep disorder. Among its related pathways are Signaling by GPCR and Signaling by GPCR. GO annotations related to this gene include histamine receptor activity. An important paralog of this gene is CHRM4.
UniProtKB/Swiss-Prot for HRH3 Gene
The H3 subclass of histamine receptors could mediate the histamine signals in CNS and peripheral nervous system. Signals through the inhibition of adenylate cyclase and displays high constitutive activity (spontaneous activity in the absence of agonist). Agonist stimulation of isoform 3 neither modified adenylate cyclase activity nor induced intracellular calcium mobilization
Histamine H3 receptors are Galphai/o-protein-coupled receptors first cloned in 1999. H3 receptors are expressed at high levels on histaminergic neurons in the central nervous system, particularly in the basal ganglia, cortex, hippocampus and strial area. They are expressed in the periphery at lower densities in the gastrointestinal, bronchial and cardiovascular systems. H3 receptors are thought to function as presynaptic autoreceptors, and activation stimulates the negative feedback mechanism that reduces central histaminergic activity. These receptors have displayed heterogeneity in binding and functional studies, suggesting multiple subtypes. In rats, three H3 receptor subtypes have been indentified and they all vary in the length of the third extracellular loop, have distinct CNS localization and differentially couple to adenylyl cyclase and MAPK signaling pathways. H3 receptors have multiple functions including roles in cognition, sleep-wake status, energy homeostasis regulation and inflammation. Activation of these receptors can inhibit histamine, dopamine, serotonin, noradrenalin and acetylcholine release and they participate in control of neurogenic inflammation through local-neuron feedback loops. Furthermore, H3 receptor activation increases antigen-presenting cell capacity. H3 receptors are thought to have pathophysiological relevance and are involved in cognitive impairment, seizures and possibly metabolic syndrome. The human gene encoding this receptor is localized to chromosome 20q13.33.