Opioid growth factor receptor, also known as OGFr or the ζ-opioid receptor, is a protein which in humans is encoded by the OGFRgene.[5][6] The protein encoded by this gene is a receptor for opioid growth factor (OGF), also known as [Met(5)]-enkephalin. The endogenous ligand is thus a known opioid peptide, and OGFr was originally discovered and named as a new opioid receptor zeta (ζ). However it was subsequently found that it shares little sequence similarity with the other opioid receptors, and has quite different function.
^Zagon IS, Verderame MF, Allen SS, McLaughlin PJ (February 2000). "Cloning, sequencing, chromosomal location, and function of cDNAs encoding an opioid growth factor receptor (OGFr) in humans". Brain Res. 856 (1–2): 75–83. doi:10.1016/S0006-8993(99)02330-6. PMID10677613. S2CID37516655.
