database / hormone
Orexin-A
also known as hypocretin-1
Skeletal structure drawn from the computed atomic coordinates in PubChem CID 56842143. Carbons are implicit vertices, hydrogens on carbon suppressed. Every atom sits where PubChem placed it.
Sequence
Primary structure not characterised in the public record.
Pyroglutamate N-terminus, C-terminal amide, and two intrachain disulfide bonds.
Molecular data
| molecular formula | C152H243N47O44S4 |
|---|---|
| molecular weight | 3561.1 Da (PubChem) |
| computed backbone mass | not characterised |
| length | not characterised |
| net charge (pH 7.4) | not characterised |
| mean hydropathy | not characterised |
| half-life | not characterised |
| delivery route | not characterised |
| PubChem CID | 56842143 |
| PDB | not characterised |
| UniProt parent | O43612 |
Mechanism
OX1R/OX2R agonist; central regulator of arousal and wakefulness.
Reported targets: OX1R OX2R
Experimental structure
No experimental structure deposited in the PDB. A predicted fold is not a structure, so nothing is drawn.
Parent protein
Orexin-A and orexin-B share a precursor. UniProt O43612 · 131 aa
Reported effects
Each row is an outcome described in the literature indexed for this peptide.
| reported outcome | where it appears |
|---|---|
| wakefulness in models | Identification and quantification of Hypocretin-1/Orexin-A 1-14 and 1-16 fra… Sleep medicine 2026 |
| appetite effects in models | 16-mer hypocretin-1/orexin-A in cerebrospinal fluid to diagnose narcolepsy Sleep 2025 |
Registered trials
| NCT | title | status | phase |
|---|---|---|---|
| NCT05446025 | The Levels of the Orexin, Galanin and aMSH and CART in Patients With Hyperemesis Gravidarum | COMPLETED | — |
| NCT03947281 | Snacks and Satiety | TERMINATED | NA |
| NCT01638403 | Effects of BF2.649 in the Treatment of Excessive Daytime Sleepiness in Narcolepsy. | COMPLETED | PHASE3 |
| NCT03025295 | The Effect of Orexin on Delayed Emergence of General Anesthesia in Dexmedetomidine | COMPLETED | NA |
| NCT05795270 | Multicenter Study on the Role of Neurodegeneration Biomarkers in Obstructive Sleep Apnea Syn | UNKNOWN | — |
Literature (7)
Identification and quantification of Hypocretin-1/Orexin-A 1-14 and 1-16 fragments in immunopurified cerebrospinal fluid using LC-MS: Comparison with radioimmunoassay (RIA) determinations — Sleep medicine 2026
abstract not reproduced — this record is not open-access, so it is linked rather than copied.
publisher record ↗ · PMID 42127723 · DOI 10.1016/j.sleep.2026.109006
16-mer hypocretin-1/orexin-A in cerebrospinal fluid to diagnose narcolepsy — Sleep 2025
abstract not reproduced — this record is not open-access, so it is linked rather than copied.
publisher record ↗ · PMID 40801283 · DOI 10.1093/sleep/zsaf237
Hypocretin-1/ Orexin-A fragment1-16 as a potential surrogate marker for diagnosing narcolepsy type 1 — Sleep 2026
abstract not reproduced — this record is not open-access, so it is linked rather than copied.
publisher record ↗ · PMID 42139087 · DOI 10.1093/sleep/zsag115
Detection of reduced orexin-A/hypocretin-1 and its fragments by orexin-A "gold-standard" radioimmunoassay — Sleep medicine 2025
abstract not reproduced — this record is not open-access, so it is linked rather than copied.
publisher record ↗ · PMID 40250157 · DOI 10.1016/j.sleep.2025.106505
Unravelling Narcolepsy: A Series of Complex Pediatric Cases — Neurology. Clinical practice 2026
abstract not reproduced — this record is not open-access, so it is linked rather than copied.
publisher record ↗ · PMID 41669756 · DOI 10.1212/cpj.0000000000200583
Pediatric Narcolepsy — StatPearls Publishing, Treasure Island (FL) 2026
Sleep plays a critical role in brain maturation. In the developing brain, sleep impairment profoundly alters the regulation of monoamines, acetylcholine, and neuropeptides, disrupts toxin clearance through the glymphatic system, and interferes with hormonal balance and inflammatory processes. Sleep-wake disorders include insomnia, obstructive sleep apnea, parasomnias, narcolepsy, and restless leg syndrome. Narcolepsy represents a chronic condition characterized by severe excessive daytime sleepiness (EDS). The ICSD-3 classifies narcolepsy into 2 types: type 1, which includes cataplexy, and type 2, which lacks cataplexy. Both types present with persistent fatigue and impaired ability to maintain wakefulness during the day. REM sleep characteristics aid in distinguishing narcolepsy from other central hypersomnolence disorders and in differentiating type 1 from type 2. Rapid eye movement (R…
open access ↗ · PMID 42044244
The orexin system as a pharmacological target in inflammation: peripheral mechanisms and safety implications — Frontiers in pharmacology 2026
abstract not reproduced — this record is not open-access, so it is linked rather than copied.
publisher record ↗ · PMID 42609337 · DOI 10.3389/fphar.2026.1831913
The mechanism, illustrated
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