OGFr

Opioid growth factor receptor, also known as OGFr or the ζ-opioid receptor, is a is_associated_with::protein which in humans is encoded by the OGFR is_associated_with::gene. 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 is_associated_with::opioid peptide, and OGFr was originally discovered and named as a new is_associated_with::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.

Function
The natural function of this receptor appears to be in regulation of tissue growth,   and it has been shown to be important in embryonic development, wound repair, and certain forms of cancer.

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.

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

Structure
OGF contains a conserved is_associated_with::N-terminal domain followed by a series of imperfect repeats.