FEATURES

FAMILY

DESCRIPTION

Also known as OPRM_MOUSE, Oprm1, Mor, Oprm. Receptor for endogenous opioids such as beta-endorphin and endomorphin. Receptor for natural and synthetic opioids including morphine, heroin, DAMGO, fentanyl, etorphine, buprenorphin and methadone. Agonist binding to the receptor induces coupling to an inactive GDP-bound heterotrimeric G-protein complex and subsequent exchange of GDP for GTP in the G-protein alpha subunit leading to dissociation of the G-protein complex with the free GTP-bound G-protein alpha and the G-protein beta-gamma dimer activating downstream cellular effectors. The agonist- and cell type-specific activity is predominantly coupled to pertussis toxin-sensitive G(i) and G(o) G alpha proteins, GNAI1, GNAI2, GNAI3 and GNAO1 isoforms Alpha-1 and Alpha-2, and to a lesser extent to pertussis toxin-insensitive G alpha proteins GNAZ and GNA15. They mediate an array of downstream cellular responses, including inhibition of adenylate cyclase activity and both N-type and L-type calcium channels, activation of inward rectifying potassium channels, mitogen-activated protein kinase (MAPK), phospholipase C (PLC), phosphoinositide/protein kinase (PKC), phosphoinositide 3-kinase (PI3K) and regulation of NF-kappa-B. Also couples to adenylate cyclase stimulatory G alpha proteins. The selective temporal coupling to G-proteins and subsequent signaling can be regulated by RGSZ proteins, such as RGS9, RGS17 and RGS4. Phosphorylation by members of the GPRK subfamily of Ser/Thr protein kinases and association with beta-arrestins is involved in short-term receptor desensitization. Beta-arrestins associate with the GPRK-phosphorylated receptor and uncouple it from the G-protein thus terminating signal transduction. The phosphorylated receptor is internalized through endocytosis via clathrin-coated pits which involves beta-arrestins. The activation of the ERK pathway occurs either in a G-protein-dependent or a beta-arrestin-dependent manner and is regulated by agonist-specific receptor phosphorylation. Acts as a class A G-protein coupled receptor (GPCR) which dissociates from beta-arrestin at or near the plasma membrane and undergoes rapid recycling. Receptor down-regulation pathways are varying with the agonist and occur dependent or independent of G-protein coupling. Endogenous ligands induce rapid desensitization, endocytosis and recycling. Heterooligomerization with other GPCRs can modulate agonist binding, signaling and trafficking properties. Involved in neurogenesis. Isoform 9 is involved in morphine-induced scratching and seems to cross-activate GRPR in response to morphine. Forms homooligomers and heterooligomers with other GPCRs, such as OPRD1, OPRK1, OPRL1, NPFFR2, ADRA2A, SSTR2, CNR1 and CCR5 (probably in dimeric forms) (PubMed:10842167, PubMed:12270145, PubMed:18836069, PubMed:21422164). Interacts with heterotrimeric G proteins; interaction with a heterotrimeric complex containing GNAI1, GNB1 and GNG2 stabilizes the active conformation of the receptor and increases its affinity for endomorphin-2, the synthetic opioid peptide DAMGO and for morphinan agonists (PubMed:26245379). Interacts with PPL; the interaction disrupts agonist-mediated G-protein activation. Interacts (via C-terminus) with DNAJB4 (via C-terminus). Interacts with calmodulin; the interaction inhibits the constitutive activity of OPRM1; it abolishes basal and attenuates agonist-stimulated G-protein coupling. Interacts with FLNA, PLD2, RANBP9 and WLS and GPM6A (By similarity). Interacts with RTP4 (PubMed:18836069). Interacts with SYP and GNAS (By similarity). Interacts with RGS9, RGS17, RGS20, RGS4, PPP1R9B and HINT1 (PubMed:15827571, PubMed:17725581, PubMed:18439408, PubMed:21153910). Isoform 9 interacts with GRPR (PubMed:22000021).

Also known as OPRM_MOUSE, Oprm1, Mor, Oprm. Receptor for endogenous opioids such as beta-endorphin and endomorphin. Receptor for natural and synthetic opioids including morphine, heroin, DAMGO, ...

EXTERNAL LINKS

Oprm1

Mu-type opioid receptor

Oprm1

Molecular Synopsis