• Hcrt
  • Hypocretin
  • OX
  • PPOX
Gene Name
Amino acid sequence
Number of residues
Molecular Weight
Theoretical pI
Not Available
GO Classification
eating behavior / excitatory postsynaptic potential / negative regulation of DNA replication / negative regulation of potassium ion transport / negative regulation of transmission of nerve impulse / neuropeptide signaling pathway / phospholipase C-activating G-protein coupled receptor signaling pathway / positive regulation of calcium ion transport / positive regulation of cytosolic calcium ion concentration / positive regulation of transmission of nerve impulse / protein kinase C-activating G-protein coupled receptor signaling pathway / regulation of neurotransmitter secretion / synaptic transmission
cell junction / cytosol / extracellular region / perinuclear region of cytoplasm / rough endoplasmic reticulum / secretory granule / synaptic vesicle
General Function
Not Available
Specific Function
Neuropeptides that play a significant role in the regulation of food intake and sleep-wakefulness, possibly by coordinating the complex behavioral and physiologic responses of these complementary homeostatic functions. A broader role in the homeostatic regulation of energy metabolism, autonomic function, hormonal balance and the regulation of body fluids, is also suggested. Orexin-A binds to both OX1R and OX2R with a high affinity, whereas orexin-B binds only to OX2R with a similar high affinity.
Pfam Domain Function
Transmembrane Regions
Not Available
Cellular Location
Rough endoplasmic reticulum
Gene sequence
>lcl|BSEQ0013111|Orexin (HCRT)
Chromosome Location
Not Available
External Identifiers
UniProtKB IDO43612
UniProtKB Entry NameOREX_HUMAN
General References
  1. Sakurai T, Amemiya A, Ishii M, Matsuzaki I, Chemelli RM, Tanaka H, Williams SC, Richardson JA, Kozlowski GP, Wilson S, Arch JR, Buckingham RE, Haynes AC, Carr SA, Annan RS, McNulty DE, Liu WS, Terrett JA, Elshourbagy NA, Bergsma DJ, Yanagisawa M: Orexins and orexin receptors: a family of hypothalamic neuropeptides and G protein-coupled receptors that regulate feeding behavior. Cell. 1998 Feb 20;92(4):573-85. [Article]
  2. Sakurai T, Moriguchi T, Furuya K, Kajiwara N, Nakamura T, Yanagisawa M, Goto K: Structure and function of human prepro-orexin gene. J Biol Chem. 1999 Jun 18;274(25):17771-6. [Article]
  3. Lee JH, Bang E, Chae KJ, Kim JY, Lee DW, Lee W: Solution structure of a new hypothalamic neuropeptide, human hypocretin-2/orexin-B. Eur J Biochem. 1999 Dec;266(3):831-9. [Article]
  4. Hungs M, Mignot E: Hypocretin/orexin, sleep and narcolepsy. Bioessays. 2001 May;23(5):397-408. [Article]
  5. Willie JT, Chemelli RM, Sinton CM, Yanagisawa M: To eat or to sleep? Orexin in the regulation of feeding and wakefulness. Annu Rev Neurosci. 2001;24:429-58. [Article]
  6. Kim HY, Hong E, Kim JI, Lee W: Solution structure of human orexin-A: regulator of appetite and wakefulness. J Biochem Mol Biol. 2004 Sep 30;37(5):565-73. [Article]
  7. Siebold C, Hansen BE, Wyer JR, Harlos K, Esnouf RE, Svejgaard A, Bell JI, Strominger JL, Jones EY, Fugger L: Crystal structure of HLA-DQ0602 that protects against type 1 diabetes and confers strong susceptibility to narcolepsy. Proc Natl Acad Sci U S A. 2004 Feb 17;101(7):1999-2004. Epub 2004 Feb 9. [Article]
  8. Takai T, Takaya T, Nakano M, Akutsu H, Nakagawa A, Aimoto S, Nagai K, Ikegami T: Orexin-A is composed of a highly conserved C-terminal and a specific, hydrophilic N-terminal region, revealing the structural basis of specific recognition by the orexin-1 receptor. J Pept Sci. 2006 Jul;12(7):443-54. [Article]
  9. Peyron C, Faraco J, Rogers W, Ripley B, Overeem S, Charnay Y, Nevsimalova S, Aldrich M, Reynolds D, Albin R, Li R, Hungs M, Pedrazzoli M, Padigaru M, Kucherlapati M, Fan J, Maki R, Lammers GJ, Bouras C, Kucherlapati R, Nishino S, Mignot E: A mutation in a case of early onset narcolepsy and a generalized absence of hypocretin peptides in human narcoleptic brains. Nat Med. 2000 Sep;6(9):991-7. [Article]

Drug Relations

Drug Relations
DrugBank IDNameDrug groupPharmacological action?ActionsDetails
DB03088Pidolic acidapproved, investigationalunknownDetails