GPR55
Description
The GPR55 (G protein-coupled receptor 55) is a protein-coding gene located on chromosome 2.
GPR55, also known as G protein-coupled receptor 55, is a G protein-coupled receptor encoded by the GPR55 gene in humans. Along with GPR119 and GPR18, it has been implicated as a novel cannabinoid receptor. GPR55 was first identified and cloned in 1999 and later identified as a putative cannabinoid receptor due to its similar amino acid sequence in the binding region. Research groups from Glaxo Smith Kline and Astra Zeneca characterized the receptor extensively as it was thought to be responsible for the blood pressure lowering properties of cannabinoids. GPR55 is activated by endogenous and exogenous cannabinoids such as plant and synthetic cannabinoids, but GPR-55 knockout mice generated by a research group from Glaxo Smith Kline showed no altered blood pressure regulation after administration of the cannabidiol-derivative abnormal cannabidiol. GPR55 is coupled to the G-protein G13 and activation of the receptor leads to stimulation of rhoA, cdc42 and rac1. GPR55 is activated by the plant cannabinoids Δ9-THC and the endocannabinoids anandamide, 2-AG and noladin ether in the low nanomolar range. Exocannabinoids such as the synthetic cannabinoid CP-55940 are also able to activate the receptor while the structurally unrelated cannabinoid mimic WIN 55,212-2 fails to activate the receptor. Recent research suggests that lysophosphatidylinositol and its 2-arachidonoyl derivative, 2-arachidonoyl lysophosphatidylinositol (2-ALPI), may be the endogenous ligands for GPR55 and the receptor appears likely to be a possible target for treatment of inflammation and pain as with the other cannabinoid receptors.
G protein-coupled receptor that binds to several ligands including 2-arachidonoyl lysophosphatidylinositol or lysophosphatidylglucoside with high affinity, leading to rapid and transient activation of numerous intracellular signaling pathways. Induces the Ca(2+) release from intracellular stores via ERK, the heterotrimeric G protein GNA13 and RHOA leading to morphological changes including cell rounding and stress fiber formation. In macrophages, acts downstream of lysophosphatidylglucoside to inhibit the translocation of the phospholipid-transporting ABCA1 to plasma membrane and subsequent cholesterol efflux leading to lipid accumulation and foam cell formation.
GPR55 is also known as LPIR1.
