catalysed by sphingosine kinases (SphKs). The molecule is reported to have high affinity to the GPR3 receptor. The proposed ligand activates the Gs signaling pathway in oocytes. Diphenyleneiodonium chloride Diphenyleneiodonium chloride (DPI) is an inhibitor of NADPH oxidase and a potent, irreversible, and time and temperature-dependent iNOS/eNOS inhibitor. Diphenyleneiodonium chloride (DPI) also functions as a TRPA1 activator and selectively inhibits intracellular reactive oxygen species (ROS). Diphenyleneiodonium chloride (DPI) was identified as a novel agonist of GPR3 with weak or no cross-reactivity with other GPCRs. DPI was further characterized to activate several GPR3-mediated signal transduction pathways, including Ca(2+) mobilization, cAMP accumulation, membrane recruitment of β-arrestin2, and receptor desensitization. Inverse agonists Cannabidiol Cannabidiol (CBD) is a Phyto-cannabinoid found in the cannabis plant. This compound is connected to improving anxiety, cognition, and pain. Although it is orphan, GPR3 is phylogenetically most closely related to the cannabinoid receptors. Using β-arrestin2 recruitment and cAMP accumulation assays, it was recently found that cannabidiol is an inverse agonist for GPR3. The affects that the inverse agonist has are still unknown. References Further reading G protein-coupled receptors