Orexin receptor 1 (IPR004059)

Short name: Orexin_rcpt_1

Overlapping homologous superfamilies


Family relationships


The neuropeptide hormone orexin stimulates appetite and food consumption [PMID: 9656726], and is found in the hypothalamus, which has been shown to be the 'feeding centre' and plays a central role in the integrated control of feeding and energy homeostasis [PMID: 9491897]. It also has a prominent role in promoting wakefulness [PMID: 10458611, PMID: 10615891, PMID: 10481909]. The orexin receptor (also referred to as the hypocretin receptor) is a rhodopsin-like G protein-coupled receptor that binds orexin. There are two subtypes; orexin receptor 1 (OX1) and orexin receptor 2 (OX2) [PMID: 16507882].

This entry represents orexin receptor 1, it is found in many mammalian tissues [PMID: 21216246] but is mainly expressed in the hypothalamus. CNS expression includes nuclei that are involved in arousal and sleep/wake regulation, as well reward signaling. Orexin-A and B neuropeptides have different affinities for Orexin receptor subtypes [PMID: 9491897]. Receptor activation results in elevated intracellular calcium levels mediated by Gq and phospholipase C induction, but contributions from Gs and Gi mediated regulation of cAMP levels as well as non-selective cation channels have also been described [PMID: 10498827, PMID: 20002100, PMID: 12208495]. OX1 receptor signaling in sleep/wake regulation is not as well defined as for the OX2 receptor, but it has been implicated in feeding, water intake, spatial learning and reward pathways [PMID: 11102651, PMID: 11298806, PMID: 16815564].

GO terms

Biological Process

GO:0007186 G-protein coupled receptor signaling pathway
GO:0007631 feeding behavior

Molecular Function

GO:0016499 orexin receptor activity

Cellular Component

GO:0016021 integral component of membrane

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.