Opioid Receptor Kappa 1 (OPRk1)

The κ-Opioid receptor is a type of opioid receptor which binds the peptide opioid dynorphin as the primary endogenous ligand. κ receptors are widely distributed in the brain (hypothalamus, periaqueductal gray, and claustrum), spinal cord (substantia gelatinosa), and in pain neurons.

Based on receptor binding studies, three variants of the κ-opioid receptor designated κ₁, κ₂, and κ₃ have been characterized. However only one cDNA clone has been identified, hence these receptor subtypes likely arise from interaction of one κ-opioid receptor protein with other membrane associated proteins.κ-Opioid receptor ligands are also known for their characteristic diuretic effects, due to their negative regulation of antidiuretic hormone (ADH).