9LFA: Human bradykinin receptor B1R

Cryo-EM structure of human bradykinin receptor B1R bound to antagonist ELN441958. Determined by electron microscopy at 3.5 Å resolution. Released 27 May 2026.

Method: Electron microscopy
Resolution: 3.5 Å
Organisms: Homo sapiens, Lama glama
Chains: 2
Atoms: 3,032
Mol. weight: 58.28 kDa
Ligands: A1EJF
Released: 27 May 2026

Explore 9LFA in 3D Show helices and sheets RCSB PDB PDBe

Secondary structure: helices and β-sheets

9LFA contains 13 α-helices and 10 β-strands across 2 chains. 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: 13 helices, 2 β-strands

Element	Residues	Length	Sheet
α-helix	32-63	32
α-helix	71-88	18
α-helix	90-98	9
α-helix	106-139	34
α-helix	147-168	22
α-helix	170-175	6
β-strand	176-181	6	1
β-strand	186-191	6	1
α-helix	196-206	11
α-helix	207-212	6
α-helix	213-230	18
α-helix	239-272	34
α-helix	274-277	4
α-helix	284-315	32
α-helix	317-326	10

Chain C: 0 helices, 8 β-strands

Element	Residues	Length	Sheet
β-strand	4-8	5	2
β-strand	21-28	8	2
β-strand	33-38	6	3
β-strand	51-53	3	3
β-strand	69-74	6	2
β-strand	79-84	6	2
β-strand	97-101	5	3
β-strand	110	1	3

Molecules and chains

Molecule	Chains	Type	Length	Organism	UniProt
B1 bradykinin receptor,Kappa-type opioid receptor	A	protein	340	Homo sapiens	P41145 (AlphaFold model), P46663 (AlphaFold model)
Nanobody 6	C	protein	171	Lama glama

Sequence of entity 1 (A), FASTA

>9LFA_1 B1 bradykinin receptor,Kappa-type opioid receptor (chains A)
ASSWPPLELQSSNQSQLFPQNATACDNAPEAWDLLHRVLPTFIISICFFGLLGNLFVLLV
FLLPRRQLNVAEIYLANLAASDLVFVLGLPFWAENIWNQFNWPFGALLCRVINGVIKANL
FIKIFLVVAICQDRYRVLVHPMASRRQQRRRQARVTCVLIWVVGGLLSIPTFLLRSIQAV
PDLNITACILLLPHEAWHFARIVELNILGFLLPLAAIVFFNYHILASLRTVRLLSGSREK
DRNLRRITRLVLVVVVAFLVCWAPYHFFAFLEFLFQVQAVRGCFWEDFIDLGLQLANFFA
FTNSSLNPVIYVFVGRLFRTKVWELYKQCTPKSLAPISSS

Sequence of entity 2 (C), FASTA

>9LFA_2 Nanobody 6 (chains C)
MLLVNQSHQGFNKEHTSKMVSAIVLYVLLAAAAHSAFAMAQVQLQESGGGLVQAGESLRL
SCAASGTIFRLYDMGWYRRVSGNQRELVASITSGGSTKYGDSVKGRFTISRDNAKNTVYL
QMSSLKPEDTAVYYCNAEYRTGIWEELLDGWGQGTQVTVSSHHHHHHEPEA

Ligands and cofactors

ID	Name	Formula	Copies
A1EJF	7-chloranyl-2-[3-[(9-pyridin-4-yl-3,9-diazaspiro[5.5]undecan-3-yl)carbonyl]phen…	C29 H29 Cl N4 O2	1

Primary citation

Cryo-EM structure of human bradykinin receptor B1R bound to antagonist ELN441958. Xia, M., Zhang, H. To be published.

Other PDB entries of the same protein (UniProt P41145 (AlphaFold model), which also has an AlphaFold model), best resolution first:

7UL2 2.4 Å, CryoEM Structure of Inactive NTSR1 Bound to SR48692 and Nb6
22ES 2.43 Å, Gi bound kappa-opioid receptor in complex with difelikefalin
7T10 2.5 Å, CryoEM structure of somatostatin receptor 2 in complex with somatostatin-14 and Gi3
9PA4 2.5 Å, (S)-ketamine bound kappa-opioid receptor in complex with Gi1
8FEG 2.54 Å, CryoEM structure of Kappa Opioid Receptor bound to a semi-peptide and Gi1
9XDR 2.58 Å, Cryo-EM structure of asimadoline-BMS-986187-bound KOR-Gi1 complex
9ZZO 2.6 Å, MP1104-bound Kappa Opioid Receptor in complex with beta-arrestin1
8DZR 2.61 Å, GR89,696 bound Kappa Opioid Receptor in complex with gustducin
9PA1 2.63 Å, PCP bound kappa-opioid receptor in complex with Gi1
8DZS 2.65 Å, GR89,696 bound Kappa Opioid Receptor in complex with Gz
7T11 2.7 Å, CryoEM structure of somatostatin receptor 2 in complex with Octreotide and Gi3.
8DZP 2.71 Å, momSalB bound Kappa Opioid Receptor in complex with Gi1

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