Home for an orphan endorphin

A peptide which binds to the opioid receptor-like 1 (ORL1), extracted from rat's brain, increases the reactivity to pain. The sensitivity of the rat to pain decreases if the activity of ORL1 is suppressed. The peptide consists of 17 amino acids and posses a structure similar to dynorphin A. The precursor of the peptide is formed in the brain as a larger polyprotein molecule. This peptide has been named noniception and is the only peptide to bind to ORL1.