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κ receptor

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Target not currently curated in GtoImmuPdb

Target id: 318

Nomenclature: κ receptor

Family: Opioid receptors

Contents:

Gene and Protein Information Click here for help
class A G protein-coupled receptor
Species TM AA Chromosomal Location Gene Symbol Gene Name Reference
Human 7 380 8q11.23 OPRK1 opioid receptor kappa 1 65,103,135
Mouse 7 380 1 1.89 cM Oprk1 opioid receptor, kappa 1 8,47,61,77,128
Rat 7 380 5q12 Oprk1 opioid receptor, kappa 1 16,59,67-68,76
Previous and Unofficial Names Click here for help
KOR-1 | Kappa receptor | OP2 | KOP | KOPr
Database Links Click here for help
Specialist databases
GPCRdb oprk_human (Hs), oprk_mouse (Mm), oprk_rat (Rn)
Other databases
Alphafold P41145 (Hs), P33534 (Mm), P34975 (Rn)
ChEMBL Target CHEMBL237 (Hs), CHEMBL4329 (Mm), CHEMBL3614 (Rn)
DrugBank Target P41145 (Hs)
Ensembl Gene ENSG00000082556 (Hs), ENSMUSG00000025905 (Mm), ENSRNOG00000007647 (Rn)
Entrez Gene 4986 (Hs), 18387 (Mm), 29335 (Rn)
Human Protein Atlas ENSG00000082556 (Hs)
KEGG Gene hsa:4986 (Hs), mmu:18387 (Mm), rno:29335 (Rn)
OMIM 165196 (Hs)
Pharos P41145 (Hs)
RefSeq Nucleotide NM_000912 (Hs), NM_011011 (Mm), NM_017167 (Rn)
RefSeq Protein NP_000903 (Hs), NP_035141 (Mm), NP_058863 (Rn)
SynPHARM 83653 (in complex with JDTic)
83652 (in complex with JDTic)
UniProtKB P41145 (Hs), P33534 (Mm), P34975 (Rn)
Wikipedia OPRK1 (Hs)
Selected 3D Structures Click here for help
Image of receptor 3D structure from RCSB PDB
Description:  Structure of the human kappa opioid receptor in complex with JDTic
PDB Id:  4DJH
Ligand:  JDTic
Resolution:  2.9Å
Species:  Human
References:  127
Image of receptor 3D structure from RCSB PDB
Description:  Structure of the Nanobody-Stabilized Active State of the Kappa Opioid Receptor
PDB Id:  6B73
Ligand:  MP1104
Resolution:  3.1Å
Species:  Human
References:  15
Natural/Endogenous Ligands Click here for help
big dynorphin {Sp: Human, Mouse, Rat}
dynorphin A-(1-13) {Sp: Human, Mouse, Rat}
dynorphin A {Sp: Human, Mouse, Rat}
dynorphin A-(1-8) {Sp: Human, Mouse, Rat}
dynorphin B {Sp: Human, Mouse, Rat}
β-endorphin {Sp: Human} , β-endorphin {Sp: Mouse} , β-endorphin {Sp: Rat}
[Leu]enkephalin {Sp: Human, Mouse, Rat}
[Met]enkephalin {Sp: Human, Mouse, Rat}
α-neoendorphin {Sp: Human, Mouse, Rat}
β-neoendorphin {Sp: Human, Mouse, Rat}
Comments: Dynorphin A and big dynorphin are the highest potency endogenous ligands
Principal endogenous agonists (Human)
big dynorphin (PDYN, P01213), dynorphin A (PDYN, P01213)

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Agonists
Key to terms and symbols View all chemical structures Click column headers to sort
Ligand Sp. Action Value Parameter Reference
nalfurafine Small molecule or natural product Ligand has a PDB structure Hs Full agonist 10.1 pKd 124
⤷ pKd 10.1 [124]
ethylketocyclazocine Small molecule or natural product Click here for species-specific activity table Hs Full agonist 9.4 pKd 116,136
⤷ pKd 9.4 [116,136]
enadoline Small molecule or natural product Hs Full agonist 8.6 – 9.2 pKd 35
⤷ pKd 8.6 – 9.2 [35]
[3H]U69593 Small molecule or natural product Ligand is labelled Ligand is radioactive Hs Full agonist 8.7 – 8.8 pKd 51,82,103
⤷ pKd 8.7 – 8.8 (Kd 2x10-9 – 1.6x10-9 M) [51,82,103]
(-)-bremazocine Small molecule or natural product Click here for species-specific activity table Hs Partial agonist 10.5 pKi 116
⤷ pKi 10.5 [116]
ICI-199441 Small molecule or natural product Click here for species-specific activity table Hs Agonist 10.4 pKi 50
⤷ pKi 10.4 (Ki 4x10-11 M) [50]
Description: Displacement of [3H]diprenorphine from human κ opioid receptor
dynorphin A {Sp: Human, Mouse, Rat} Peptide Ligand is endogenous in the given species Rn Full agonist 10.0 – 10.3 pKi 59,67
⤷ pKi 10.0 – 10.3 [59,67]
(-)-cyclazocine Small molecule or natural product Click here for species-specific activity table Hs Partial agonist 10.0 pKi 116
⤷ pKi 10.0 [116]
ethylketocyclazocine Small molecule or natural product Click here for species-specific activity table Hs Full agonist 10.0 pKi 116
⤷ pKi 10.0 [116]
dynorphin A-(1-13) {Sp: Human, Mouse, Rat} Peptide Click here for species-specific activity table Ligand is endogenous in the given species Hs Full agonist 9.3 – 10.7 pKi 82,116
⤷ pKi 9.3 – 10.7 [82,116]
butorphanol Small molecule or natural product Approved drug Primary target of this compound Click here for species-specific activity table Hs Partial agonist 9.9 pKi 24
⤷ pKi 9.9 (Ki 1.2x10-10 M) [24]
Description: Displacement of [3H]U69593 from human κ opioid receptor expressed in CHO cells.
dynorphin A-(1-13) {Sp: Human, Mouse, Rat} Peptide Ligand is endogenous in the given species Rn Full agonist 9.9 pKi 67
⤷ pKi 9.9 [67]
dynorphin-(1-11) Peptide Click here for species-specific activity table Hs Full agonist 9.7 pKi 116
⤷ pKi 9.7 [116]
etorphine Small molecule or natural product Click here for species-specific activity table Hs Full agonist 9.7 pKi 116
⤷ pKi 9.7 [116]
GR 89696 Small molecule or natural product Hs Full agonist 9.7 pKi 89
⤷ pKi 9.7 [89]
enadoline Small molecule or natural product Hs Full agonist 9.6 pKi 40,74
⤷ pKi 9.6 [40,74]
probe 1.1 [PMID: 24187130] Small molecule or natural product Hs Agonist 9.6 pKi 134
⤷ pKi 9.6 (Ki 2.5x10-10 M) [134]
dynorphin A {Sp: Human, Mouse, Rat} Peptide Click here for species-specific activity table Ligand is endogenous in the given species Hs Full agonist 8.3 – 10.8 pKi 82,103,116,135-136
⤷ pKi 8.3 – 10.8 [82,103,116,135-136]
dynorphin B {Sp: Human, Mouse, Rat} Peptide Ligand is endogenous in the given species Rn Full agonist 9.5 pKi 67
⤷ pKi 9.5 [67]
U69593 Small molecule or natural product Hs Full agonist 9.5 pKi 51,116
⤷ pKi 9.5 [51,116]
naloxone benzoylhydrazone Small molecule or natural product Click here for species-specific activity table Hs Partial agonist 9.5 pKi 116
⤷ pKi 9.5 [116]
MP1104 Small molecule or natural product Hs Agonist 9.5 pKi 15
⤷ pKi 9.5 (Ki 3.3x10-10 M) [15]
probe 2.1 [PMID: 24187130] Small molecule or natural product Hs Agonist 9.5 pKi 134
⤷ pKi 9.5 (Ki 3.5x10-10 M) [134]
α-neoendorphin {Sp: Human, Mouse, Rat} Peptide Ligand is endogenous in the given species Rn Full agonist 8.9 – 10.0 pKi 59,67
⤷ pKi 8.9 – 10.0 [59,67]
HS665 Small molecule or natural product Primary target of this compound Click here for species-specific activity table Hs Full agonist 9.3 pKi 108
⤷ pKi 9.3 (Ki 4.9x10-10 M) [108]
α-neoendorphin {Sp: Human, Mouse, Rat} Peptide Ligand is endogenous in the given species Hs Full agonist 8.3 – 10.2 pKi 103,135
⤷ pKi 8.3 – 10.2 [103,135]
β-neoendorphin {Sp: Human, Mouse, Rat} Peptide Ligand is endogenous in the given species Rn Full agonist 9.1 pKi 67
⤷ pKi 9.1 [67]
E2078 Peptide Hs Full agonist 9.1 pKi 90
⤷ pKi 9.1 [90]
dynorphin B {Sp: Human, Mouse, Rat} Peptide Click here for species-specific activity table Ligand is endogenous in the given species Hs Partial agonist 8.1 – 9.9 pKi 82,103,116
⤷ pKi 8.1 – 9.9 [82,103,116]
spiradoline Small molecule or natural product Rn Full agonist 9.0 pKi 16
⤷ pKi 9.0 [16]
asimadoline Small molecule or natural product Immunopharmacology Ligand Cp Agonist 9.0 pKi 30
⤷ pKi 9.0 (Ki 1x10-9 M) [30]
Description: Displacement of [3H]- 69593 from K opioid receptors from guinea pig cerebellum.
dynorphin A-(1-8) {Sp: Human, Mouse, Rat} Peptide Click here for species-specific activity table Ligand is endogenous in the given species Hs Full agonist 8.0 – 9.9 pKi 82,103,116,129
⤷ pKi 8.0 – 9.9 [82,103,116,129]
ethylketocyclazocine Small molecule or natural product Rn Full agonist 8.8 pKi 67
⤷ pKi 8.8 [67]
E2078 Peptide Rn Full agonist 8.8 pKi 67
⤷ pKi 8.8 [67]
ICI 204448 Small molecule or natural product Rn Full agonist 8.8 pKi 16
⤷ pKi 8.8 [16]
tifluadom Small molecule or natural product Hs Full agonist 8.8 pKi 136
⤷ pKi 8.8 [136]
U50488 Small molecule or natural product Hs Agonist 7.8 – 9.7 pKi 14,82,103,116,123,135-136
⤷ pKi 7.8 – 9.7 [14,82,103,116,123,135-136]
cebranopadol Small molecule or natural product Click here for species-specific activity table Hs Agonist 8.6 pKi 60
⤷ pKi 8.6 (Ki 2.6x10-9 M) [60]
Description: Radioligand binding assay
hydromorphone Small molecule or natural product Approved drug Click here for species-specific activity table Hs Agonist 8.6 pKi 125
⤷ pKi 8.6 (Ki 2.8x10-9 M) [125]
nalorphine Small molecule or natural product Approved drug Click here for species-specific activity table Hs Partial agonist 7.9 – 9.1 pKi 116,136
⤷ pKi 7.9 – 9.1 [116,136]
U50488 Small molecule or natural product Rn Partial agonist 8.2 – 8.7 pKi 16,59,67
⤷ pKi 8.2 – 8.7 [16,59,67]
U69593 Small molecule or natural product Rn Full agonist 8.0 – 8.7 pKi 16,67
⤷ pKi 8.0 – 8.7 [16,67]
salvinorin A Small molecule or natural product Hs Full agonist 7.8 – 8.7 pKi 11,94
⤷ pKi 7.8 – 8.7 [11,94]
BU08028 Small molecule or natural product Click here for species-specific activity table Hs Agonist 8.3 pKi 44
⤷ pKi 8.3 (Ki 5.63x10-9 M) [44]
compound 3 [PMID: 23134120] Small molecule or natural product Click here for species-specific activity table Hs Partial agonist 8.2 pKi 108
⤷ pKi 8.2 (Ki 5.9x10-9 M) [108]
(-)-pentazocine Small molecule or natural product Approved drug Click here for species-specific activity table Hs Partial agonist 7.8 – 8.6 pKi 116,136
⤷ pKi 7.8 – 8.6 [116,136]
β-neoendorphin {Sp: Human, Mouse, Rat} Peptide Ligand is endogenous in the given species Hs Full agonist 7.9 pKi 103
⤷ pKi 7.9 [103]
tramadol Small molecule or natural product Approved drug Click here for species-specific activity table Hs Agonist 7.8 pKi 125
⤷ pKi 7.8 (Ki 1.4x10-8 M) [125]
Description: Displacement of the kappa agonist U69593 from the kappa receptor expressed in CHO cells.
normorphine Small molecule or natural product Click here for species-specific activity table Hs Full agonist 7.8 pKi 116
⤷ pKi 7.8 [116]
ADL5747 Small molecule or natural product Click here for species-specific activity table Hs Agonist 7.6 pKi 56
⤷ pKi 7.6 (Ki 2.5x10-8 M) [56]
BW373U86 Small molecule or natural product Click here for species-specific activity table Rn Agonist 7.5 pKi 12
⤷ pKi 7.5 (Ki 3.4x10-8 M) [12]
nalbuphine Small molecule or natural product Approved drug Primary target of this compound Click here for species-specific activity table Hs Full agonist 7.4 – 7.5 pKi 136
⤷ pKi 7.4 – 7.5 [136]
ADL5859 Small molecule or natural product Click here for species-specific activity table Hs Agonist 7.4 pKi 55
⤷ pKi 7.4 (Ki 3.7x10-8 M) [55]
carfentanil Small molecule or natural product Click here for species-specific activity table Ligand has a PDB structure Cp Agonist 7.4 pKi 17
⤷ pKi 7.4 (Ki 4.31x10-8 M) [17]
Description: Binding affinity- displacement of [3H]U69593 in guinea pig whole brain
morphine Small molecule or natural product Approved drug Click here for species-specific activity table Ligand has a PDB structure Hs Partial agonist 7.3 pKi 116
⤷ pKi 7.3 [116]
cebranopadol Small molecule or natural product Click here for species-specific activity table Rn Agonist 7.2 pKi 60
⤷ pKi 7.2 (Ki 6.4x10-8 M) [60]
Description: Radioligand binding assay
β-endorphin {Sp: Human} Peptide Click here for species-specific activity table Ligand is endogenous in the given species Hs Partial agonist 6.3 – 7.9 pKi 103,116
⤷ pKi 6.3 – 7.9 [103,116]
dihydromorphine Small molecule or natural product Click here for species-specific activity table Hs Partial agonist 7.1 pKi 116
⤷ pKi 7.1 [116]
fentanyl Small molecule or natural product Approved drug Click here for species-specific activity table Ligand has a PDB structure Hs Partial agonist 7.1 pKi 116
⤷ pKi 7.1 [116]
etonitazene Small molecule or natural product Click here for species-specific activity table Hs Partial agonist 6.9 pKi 116
⤷ pKi 6.9 [116]
BW373U86 Small molecule or natural product Click here for species-specific activity table Hs Agonist 6.9 pKi 55
⤷ pKi 6.9 (Ki 1.3x10-7 M) [55]
SCH221510 Small molecule or natural product Click here for species-specific activity table Hs Agonist 6.9 pKi 121
⤷ pKi 6.9 (Ki 1.31x10-7 M) [121]
Description: Radioligand binding assay
morphine Small molecule or natural product Approved drug Click here for species-specific activity table Ligand has a PDB structure Rn Partial agonist 6.7 – 7.0 pKi 16,67
⤷ pKi 6.7 – 7.0 [16,67]
β-endorphin {Sp: Human} Peptide Click here for species-specific activity table Rn Full agonist 6.8 pKi 67
⤷ pKi 6.8 [67]
UFP-512 Small molecule or natural product Click here for species-specific activity table Hs Agonist 6.7 pKi 122
⤷ pKi 6.7 [122]
Description: Measuring displacement of [3H]-diprenorphine in vitro
hydrocodone Small molecule or natural product Approved drug Click here for species-specific activity table Hs Agonist 6.6 pKi 75
⤷ pKi 6.6 (Ki 2.6x10-7 M) [75]
(-)-methadone Small molecule or natural product Click here for species-specific activity table Hs Partial agonist 6.5 pKi 116
⤷ pKi 6.5 [116]
DAMGO Peptide Click here for species-specific activity table Hs Partial agonist 6.5 pKi 116
⤷ pKi 6.5 [116]
SR16835 Small molecule or natural product Click here for species-specific activity table Hs Agonist 6.2 pKi 117
⤷ pKi 6.2 (Ki 6.813x10-7 M) [117]
Description: Radioligand binding assay
bilorphin Small molecule or natural product Click here for species-specific activity table Hs Agonist 6.1 pKi 21
⤷ pKi 6.1 (Ki 7.7x10-7 M) [21]
[Leu]enkephalin {Sp: Human, Mouse, Rat} Peptide Ligand is endogenous in the given species Rn Full agonist 6.0 pKi 67
⤷ pKi 6.0 [67]
[Met]enkephalin {Sp: Human, Mouse, Rat} Peptide Click here for species-specific activity table Ligand is endogenous in the given species Immunopharmacology Ligand Rn Full agonist 6.0 pKi 67
⤷ pKi 6.0 [67]
DAMGO Peptide Click here for species-specific activity table Rn Partial agonist 5.9 pKi 67
⤷ pKi 5.9 [67]
difelikefalin Peptide Approved drug Immunopharmacology Ligand Mm Agonist 10.3 pEC50 99
⤷ pEC50 10.3 (EC50 4.8x10-11 M) [99]
difelikefalin Peptide Approved drug Primary target of this compound Immunopharmacology Ligand Hs Agonist 9.8 pEC50 99
⤷ pEC50 9.8 (EC50 1.6x10-10 M) [99]
HS665 Small molecule or natural product Primary target of this compound Click here for species-specific activity table Hs Full agonist 8.4 pEC50 108
⤷ pEC50 8.4 (EC50 3.62x10-9 M) [108]
Description: Measuring stimulation of [35S]GTPγS binding.
compound 3 [PMID: 23134120] Small molecule or natural product Click here for species-specific activity table Hs Partial agonist 7.5 pEC50 108
⤷ pEC50 7.5 (EC50 3.5x10-8 M) [108]
Description: Measuring stimulation of [35S]GTPγS binding.
probe 1.1 [PMID: 24187130] Small molecule or natural product Hs Biased agonist 5.4 – 7.5 pEC50 134
⤷ pEC50 7.5 (EC50 3.1x10-8 M) [134]
Description: Measuring [35S]GTPγS binding
pEC50 5.4 (EC50 4.129x10-6 M) [134]
Description: Measuring βarrestin2 recruitment
probe 2.1 [PMID: 24187130] Small molecule or natural product Hs Biased agonist 5.0 – 7.1 pEC50 134
⤷ pEC50 7.1 (EC50 8.47x10-8 M) [134]
Description: Measuring [35S]GTPγS binding
pEC50 <5.0 (EC50 >1x10-5 M) [134]
Description: Measuring βarrestin2 recruitment
α-neoendorphin {Sp: Human, Mouse, Rat} Peptide Click here for species-specific activity table Ligand is endogenous in the given species Mm Full agonist 10.0 pIC50 128
⤷ pIC50 10.0 [128]
dynorphin B {Sp: Human, Mouse, Rat} Peptide Ligand is endogenous in the given species Mm Full agonist 10.0 pIC50 128
⤷ pIC50 10.0 [128]
dynorphin A-(1-8) {Sp: Human, Mouse, Rat} Peptide Ligand is endogenous in the given species Mm Full agonist 9.7 pIC50 128
⤷ pIC50 9.7 [128]
[D-Ala2,F5,Phe4]dynorphin-(1-17)-NH2 Peptide Mm Full agonist 9.7 pIC50 128
⤷ pIC50 9.7 [128]
dynorphin-(1-17)-NH2 Peptide Mm Full agonist 9.7 pIC50 128
⤷ pIC50 9.7 [128]
(-)-bremazocine Small molecule or natural product Mm Full agonist 9.5 pIC50 128
⤷ pIC50 9.5 [128]
dynorphin A {Sp: Human, Mouse, Rat} Peptide Ligand is endogenous in the given species Mm Full agonist 9.4 pIC50 128
⤷ pIC50 9.4 [128]
[Met5]dynorphin-(1-17) Peptide Mm Full agonist 9.2 pIC50 128
⤷ pIC50 9.2 [128]
ethylketocyclazocine Small molecule or natural product Click here for species-specific activity table Mm Full agonist 9.0 pIC50 128
⤷ pIC50 9.0 [128]
U50488 Small molecule or natural product Mm Partial agonist 9.0 pIC50 128
⤷ pIC50 9.0 [128]
spiradoline Small molecule or natural product Mm Full agonist 9.0 pIC50 128
⤷ pIC50 9.0 [128]
U69593 Small molecule or natural product Mm Full agonist 8.6 pIC50 128
⤷ pIC50 8.6 [128]
ICI 204448 Small molecule or natural product Mm Full agonist 8.2 pIC50 128
⤷ pIC50 8.2 [128]
[D-Ala2,F5,Phe4]dynorphin-(1-13)-NH2 Peptide Mm Full agonist 7.7 pIC50 128
⤷ pIC50 7.7 [128]
β-endorphin {Sp: Human} Peptide Click here for species-specific activity table Mm Partial agonist 7.4 pIC50 128
⤷ pIC50 7.4 [128]
nalbuphine Small molecule or natural product Approved drug Mm Full agonist 7.4 pIC50 128
⤷ pIC50 7.4 [128]
pethidine Small molecule or natural product Approved drug Click here for species-specific activity table Hs Agonist 5.6 pIC50 87
⤷ pIC50 5.6 (IC50 2.37x10-6 M) [87]
AR-M1000390 Small molecule or natural product Click here for species-specific activity table Hs Agonist 5.1 pIC50 4
⤷ pIC50 5.1 (IC50 7.47x10-6 M) [4]
[3H]enadoline Small molecule or natural product Ligand is labelled Ligand is radioactive Hs Full agonist - - 104
⤷ [104]
View species-specific agonist tables
Agonist Comments
Ki values were determined in the absence of Na+ and GDP, except TRK820.

Discrimination of full or partial agonism is very dependent on the level of receptor expression and on the assay used to monitor agonist effects. Many agents may behave as full agonists or potent partial agonists in cell lines expressing cloned receptors in high concentration, but in other environments they may show only weak agonist activity. The identification of agonist activity in the table is largely based on the ability to stimulate GTPγS binding in cell lines expressing cloned human kappa receptors. Agents giving 85% or greater stimulation than that given by U69593 have been characterized as Full Agonists [116].

κ opioid receptors have been divided into several different subtypes, mainly on the basis of [3H]agonist binding assays. Generally 2 subtypes are recognised: κ1 and κ2. The benzeneacetamides and peptides are considered κ1 agonists and the benzomorphans bind to κ1 and κ2. However, there is only one gene product and the subtypes are considered putative.

Selective κ agonists are of several structural types. All have high affinity for the κ receptor and are full agonists.

We have tagged the μ receptor as the primary drug target for hydrocodone based on this drug having the highest affinity at this receptor compared to the κ and δ receptors [75]. Similarly, we have tagged the μ receptor as the primary target of the drug hydromorphone [125].
Antagonists
Key to terms and symbols View all chemical structures Click column headers to sort
Ligand Sp. Action Value Parameter Reference
LY2456302 Small molecule or natural product Primary target of this compound Click here for species-specific activity table Hs Antagonist 9.1 pKB 93
⤷ pKB 9.1 (KB 8.13x10-10 M) [93]
Description: Measuring inhibition of agonist-induced [35S]GTPγS binding in vitro.
zyklophin Peptide Primary target of this compound Click here for species-specific activity table Hs Antagonist 7.1 pKB 81
⤷ pKB 7.1 (KB 8.39x10-8 M) [81]
Description: Schild analysis of zyklophin vs. Dynorphin A-(1-13)NH2
[3H]diprenorphine Small molecule or natural product Click here for species-specific activity table Ligand is labelled Ligand is radioactive Hs Antagonist 9.1 pKd 3,103
⤷ pKd 9.1 (Kd 7.94x10-10 M) [3,103]
nor-binaltorphimine Small molecule or natural product Rn Antagonist 9.6 – 10.7 pKi 16,59,67
⤷ pKi 9.6 – 10.7 [16,59,67]
JDTic Small molecule or natural product Primary target of this compound Ligand has a PDB structure Hs Antagonist 9.0 – 11.2 pKi 71,114,131
⤷ pKi 11.2 (Ki 6x10-12 M) [114]
Description: Measuring antagonism of U50,488-induced [35S]GTPγS binding
pKi 9.0 – 9.4 (Ki 1x10-9 – 3.98x10-10 M) [71,114,131]
nor-binaltorphimine Small molecule or natural product Click here for species-specific activity table Hs Antagonist 8.9 – 11.0 pKi 82,86,103,116,135-136
⤷ pKi 8.9 – 11.0 [82,86,103,116,135-136]
5'-guanidinonaltrindole Small molecule or natural product Hs Antagonist 9.7 – 9.9 pKi 41,82,110
⤷ pKi 9.7 – 9.9 [41,82,110]
β-FNA Small molecule or natural product Click here for species-specific activity table Hs Antagonist 9.7 pKi 116
⤷ pKi 9.7 [116]
quadazocine Small molecule or natural product Click here for species-specific activity table Hs Antagonist 9.7 pKi 116
⤷ pKi 9.7 [116]
diprenorphine Small molecule or natural product Click here for species-specific activity table Hs Antagonist 9.6 – 9.7 pKi 82,116,135-136
⤷ pKi 9.6 – 9.7 [82,116,135-136]
buprenorphine Small molecule or natural product Approved drug Primary target of this compound Click here for species-specific activity table Hs Antagonist 9.1 – 10.2 pKi 116,136
⤷ pKi 9.1 – 10.2 [116,136]
samidorphan Small molecule or natural product Approved drug Click here for species-specific activity table Hs Antagonist 9.6 pKi 126
⤷ pKi 9.6 (Ki 2.3x10-10 M) [126]
nalmefene Small molecule or natural product Approved drug Primary target of this compound Click here for species-specific activity table Hs Antagonist 9.5 pKi 116
⤷ pKi 9.5 [116]
LY2456302 Small molecule or natural product Primary target of this compound Click here for species-specific activity table Hs Antagonist 9.1 pKi 93
⤷ pKi 9.1 (Ki 8.07x10-10 M) [93]
AT-076 Small molecule or natural product Click here for species-specific activity table Hs Antagonist 8.9 pKi 116,131
⤷ pKi 8.9 (Ki 1.14x10-9 M) [116,131]
Description: Radioligand binding assay
naltrexone Small molecule or natural product Approved drug Primary target of this compound Click here for species-specific activity table Hs Antagonist 8.4 – 9.4 pKi 82,103,116
⤷