Orexin receptor type 2 (Ox2R or OX2), also known as hypocretin receptor type 2 (HcrtR2), is a protein that in humans is encoded by the HCRTR2gene.
The structure of the receptor has been solved to 2.5 Å resolution as a fusion protein bound to suvorexant using lipid-mediated crystallization.
OX2 is a G-protein coupled receptor expressed exclusively in the brain. It has 64% identity with OX1. OX2 binds both orexin A and orexin B neuropeptides. OX2 is involved in the central feedback mechanism that regulates feeding behaviour. Mice with enhanced OX2 signaling are resistant to high-fat diet-induced obesity.
This receptor is activated by Hipocretin, which is a wake-promoting hypothalamic neuropeptide that acts as a critical regulator of sleep in animals as Zebrafish or Mammals. This protein has mutations in Astyanax mexicanus that prevents the cavefish from needing to sleep. 
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Blanco M, López M, García-Caballero T, Gallego R, Vázquez-Boquete A, Morel G, et al. (April 2001). "Cellular localization of orexin receptors in human pituitary". The Journal of Clinical Endocrinology and Metabolism. 86 (4): 1616–1619. doi:10.1210/jcem.86.7.7433. PMID11297593.
Blanco M, López M, GarcIa-Caballero T, Gallego R, Morel G, SeñarIs R, et al. (July 2001). "Cellular localization of orexin receptors in human pituitary". The Journal of Clinical Endocrinology and Metabolism. 86 (7): 1616–1619. doi:10.1210/jcem.86.7.7433. PMID11443222.