21CI: Human orexin type 2 receptor

Crystal structure of human orexin type 2 receptor in complex with vornorexant. Determined by X-ray diffraction at 3.29 Å resolution. Released 3 Jun 2026.

Method: X-ray diffraction
Resolution: 3.29 Å
Organism: Homo sapiens
Chains: 1
Atoms: 2,563
Mol. weight: 40.2 kDa
Ligands: A1MCY
Released: 3 Jun 2026

Explore 21CI in 3D Show helices and sheets RCSB PDB PDBe

Secondary structure: helices and β-sheets

21CI contains 16 α-helices and 2 β-strands across 1 chain. Residue ranges use author residue numbering, as in the PDB file, from PDBe. To see them in 3D, choose the Cartoon representation with Secondary structure coloring: helices, sheets and coils get different colors.

Chain A: 16 helices, 2 β-strands

Element	Residues	Length	Sheet
α-helix	38-48	11
α-helix	55-81	27
α-helix	88-106	19
α-helix	108-117	10
α-helix	123-156	34
α-helix	162-165	4
α-helix	166-183	18
α-helix	185-190	6
β-strand	191-194	4	1
β-strand	209-212	4	1
α-helix	219-228	10
α-helix	229-233	5
α-helix	234-251	18
α-helix	254-256	3
α-helix	290-324	35
α-helix	325-329	5
α-helix	339-367	29
α-helix	369-383	15

Molecules and chains

Molecule	Chains	Type	Length	Organism	UniProt
Orexin receptor type 2	A	protein	341	Homo sapiens	O43614 (AlphaFold model)

Sequence of entity 1 (A), FASTA

>21CI_1 Orexin receptor type 2 (chains A)
GPLEDYDDEEFLRYLWREYLHPKEYEWVLIAGYIIVFVVALIGNVLVCVAVWKNHHMRTV
TNYFIVNLSLAAVLVTITCLPATLVVDITETWFFGQSLCKVIPYLQTVSVSVSVWTLSAI
ALDRWYAICHPLMFKSTAKRARNSIVIIWIVSCIIMIPQAIVMECSTVFPGLAQKTTLFT
VCDERWGGEIYPKMYHICFFLVTYMAPLCLMVLAYLQIFRKLWCRQIPGVAAEIKQIRAR
RKTARMLMIVLLVFAICYLPISILNVLKRVFGMFAHTEDRETVYAWFTFSHWLVYANSAA
NPIIYNFLSGKFREEFKAAFSCCCLGVHHRQEDRLLEVLFQ

Ligands and cofactors

ID	Name	Formula	Copies
A1MCY	vornorexant	C23 H22 F N7 O2	1

Water and common crystallization additives (SO4) are not listed.

Primary citation

Structural insights into the binding mode of the hypnotic drug vornorexant to orexin receptors. Mima, M., Mishima-Tsumagari, C., Sakata-Sakuta, M. et al. Acta Crystallogr F Struct Biol Commun (2026) 82:201-207. DOI 10.1107/S2053230X26003432 · PubMed

Other PDB entries of the same protein (UniProt O43614 (AlphaFold model), which also has an AlphaFold model), best resolution first:

5WQC 1.96 Å, Crystal structure of human orexin 2 receptor bound to the selective antagonist EMPA…
5WS3 2.3 Å, Crystal structures of human orexin 2 receptor bound to the selective antagonist EMPA…
4S0V 2.5 Å, Crystal structure of the human OX2 orexin receptor bound to the insomnia drug Suvorexant
6TPN 2.61 Å, Crystal structure of the Orexin-2 receptor in complex with HTL6641 at 2.61 A resolution
6TPJ 2.74 Å, Crystal structure of the Orexin-2 receptor in complex with suvorexant at 2.76 A resolution
6TPG 2.74 Å, Crystal structure of the Orexin-2 receptor in complex with EMPA at 2.74 A resolution
7XRR 2.89 Å, Crystal structure of the human OX2R bound to the insomnia drug lemborexant.
7L1V 3.0 Å, Orexin Receptor 2 (OX2R) in Complex with G Protein and Small-Molecule Agonist Compound 1
7SQO 3.17 Å, Structure of the orexin-2 receptor(OX2R) bound to TAK-925, Gi and scFv16
7L1U 3.2 Å, Orexin Receptor 2 (OX2R) in Complex with G Protein and Natural Peptide-Agonist Orexin B…
7SR8 3.3 Å, Molecular mechanism of the the wake-promoting agent TAK-925

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