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RefSeq (mRNA)



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Opioid growth factor receptor (OGFr) conserved region
Opioid growth factor receptor repeat

Opioid growth factor receptor, also known as OGFr or the ζ-opioid receptor, is a protein which in humans is encoded by the OGFR gene.[1][2] 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.


The natural function of this receptor appears to be in regulation of tissue growth,[3][4][5][6] and it has been shown to be important in embryonic development,[7] wound repair,[8] and certain forms of cancer.[9][10][11][12]

OGF is a negative regulator of cell proliferation and tissue organization in a variety of processes. The encoded unbound receptor for OGF has been localized to the outer nuclear envelope, where it binds OGF and is translocated into the nucleus. The coding sequence of this gene contains a polymorphic region of 60 nt tandem imperfect repeat units. Several transcripts containing between zero and eight repeat units have been reported.[1]

Mechanism of activation

The opioid growth factor receptor consists of a chain of 677 amino acids, which includes a nuclear localization sequence region. When OGF binds to the receptor, an OGF-OGFr complex is formed, which leads to the increase in the synthesis of the selective cyclin-dependent kinase (CDK) inhibitor proteins, p12 and p16. Retinoblastoma protein becomes activated through the phosphorylation from CDKs, and leads to the progression of the cell cycle from the G1 phase to the S phase. Because the activation of the OGF receptor, blocks the phosphorylation of retinoblastmoa proteins, retardation of the G1 phase occurs, which prevents the cell from further dividing.[13][14]

Therapeutic applications

Upregulation of OGFr and consequent stimulation of the OGF-OGFr system are important for the anti-proliferative effects of imidazoquinoline drugs like imiquimod and resiquimod, which are immune response modifiers with potent antiviral and antitumour effects, used as topical creams for the treatment of skin cancers and warts.[15]


OGF contains a conserved N-terminal domain followed by a series of imperfect repeats.[4]


  1. 1.0 1.1 "Entrez Gene: OGFR opioid growth factor receptor".
  2. 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. PMID 10677613.
  3. Wu Y, McLaughlin PJ, Zagon IS (April 1998). "Ontogeny of the opioid growth factor, Met5-enkephalin, preproenkephalin gene expression, and the zeta opioid receptor in the developing and adult aorta of rat". Dev. Dyn. 211 (4): 327–37. doi:10.1002/(SICI)1097-0177(199804)211:4<327::AID-AJA4>3.0.CO;2-J. PMID 9566952.
  4. 4.0 4.1 Zagon IS, Verderame MF, McLaughlin PJ (February 2002). "The biology of the opioid growth factor receptor (OGFr)". Brain Res. Brain Res. Rev. 38 (3): 351–76. doi:10.1016/S0165-0173(01)00160-6. PMID 11890982.
  5. Malendowicz LK, Rebuffat P, Tortorella C, Nussdorfer GG, Ziolkowska A, Hochol A (May 2005). "Effects of met-enkephalin on cell proliferation in different models of adrenocortical-cell growth". Int. J. Mol. Med. 15 (5): 841–5. doi:10.3892/ijmm.15.5.841. PMID 15806307.
  6. Cheng F, McLaughlin PJ, Verderame MF, Zagon IS (January 2009). "The OGF-OGFr axis utilizes the p16INK4a and p21WAF1/CIP1 pathways to restrict normal cell proliferation". Molecular Biology of the Cell. 20 (1): 319–27. doi:10.1091/mbc.E08-07-0681. PMC 2613082. PMID 18923142.
  7. Zagon IS, Wu Y, McLaughlin PJ (August 1999). "Opioid growth factor and organ development in rat and human embryos". Brain Res. 839 (2): 313–22. doi:10.1016/S0006-8993(99)01753-9. PMID 10519055.
  8. Sassani JW, Zagon IS, McLaughlin PJ (May 2003). "Opioid growth factor modulation of corneal epithelium: uppers and downers". Curr. Eye Res. 26 (5): 249–62. doi:10.1076/ceyr. PMID 12854052.
  9. Zagon IS, Smith JP, McLaughlin PJ (March 1999). "Human pancreatic cancer cell proliferation in tissue culture is tonically inhibited by opioid growth factor". Int. J. Oncol. 14 (3): 577–84. doi:10.3892/ijo.14.3.577. PMID 10024694.
  10. McLaughlin PJ, Levin RJ, Zagon IS (May 1999). "Regulation of human head and neck squamous cell carcinoma growth in tissue culture by opioid growth factor". Int. J. Oncol. 14 (5): 991–8. doi:10.3892/ijo.14.5.991. PMID 10200353.
  11. Cheng F, Zagon IS, Verderame MF, McLaughlin PJ (November 2007). "The opioid growth factor (OGF)-OGF receptor axis uses the p16 pathway to inhibit head and neck cancer". Cancer Research. 67 (21): 10511–8. doi:10.1158/0008-5472.CAN-07-1922. PMID 17974995.
  12. Donahue RN, McLaughlin PJ, Zagon IS (March 2009). "Cell Proliferation of Human Ovarian Cancer is Regulated by the Opioid Growth Factor - Opioid Growth Factor Receptor Axis". American Journal of Physiology. Regulatory, Integrative and Comparative Physiology. 296 (6): R1716–25. doi:10.1152/ajpregu.00075.2009. PMID 19297547.
  13. Zagon IS, Donahue RN, McLaughlin PJ (2009). "Opioid growth factor-opioid growth factor receptor axis is a physiological determinant of cell proliferation in diverse human cancers". American Journal of Physiology. Regulatory, Integrative and Comparative Physiology. 297 (4): R1154–61. doi:10.1152/ajpregu.00414.2009. PMID 19675283.
  14. Avella DM, Kimchi ET, Donahue RN, Tagaram HR, McLaughlin PJ, Zagon IS, Staveley-O'Carroll KF (2010). "The opioid growth factor-opioid growth factor receptor axis regulates cell proliferation of human hepatocellular cancer". American Journal of Physiology. Regulatory, Integrative and Comparative Physiology. 298 (2): R459–66. doi:10.1152/ajpregu.00646.2009. PMC 2828179. PMID 19923357.
  15. Zagon IS, Donahue RN, Rogosnitzky M, McLaughlin PJ (August 2008). "Imiquimod upregulates the opioid growth factor receptor to inhibit cell proliferation independent of immune function". Experimental Biology and Medicine (Maywood, N.J.). 233 (8): 968–79. doi:10.3181/0802-RM-58. PMID 18480416.

Further reading

This article incorporates text from the public domain Pfam and InterPro: IPR006757
This article incorporates text from the public domain Pfam and InterPro: IPR006770