Opioid Receptor Mu 1 (OPRm1)

The μ opioid receptors (MOR) are a class of opioid receptors with high affinity for enkephalins and beta-endorphin but low affinity for dynorphins. They are also referred to as μ opioid peptide (MOP) receptors. The prototypical μ receptor agonist is the opium alkaloid morphine; μ (mu) refers to morphine.There are three well-characterized variants of the μ opioid receptor, though reverse-transcriptase PCR has identified up to 10 total splice variants in humans.More is known about the μ1 opioid receptor than is known about the other types, but some information does exist. TRIMU 5 is a selective agonist of the μ2 receptor.In 2003, a μ3 variant was described, which was responsive to opiate alkaloids but not opioid peptides.