KOR1, or Opioid receptor, kappa 1, is a human gene encoded by OPRK1. It may also be known as: Kappa-type opioid receptor; K-OR-1; KOR-1; KOR; OPRK. The encoded protein has an amino acid length of 380 and a mass of 42.6 kDa. Other isoforms may exist. KOR1 is a member of the G-protein coupled receptor 1 family. Homologs of this gene exist in other organisms, including: Mouse, Arabidopsis.