GPR55
An orphan G protein-coupled receptor activated by cannabinoids and lysophosphatidylinositol. Sometimes called the "third cannabinoid receptor."
In Depth
GPR55 is expressed in the brain, adrenal glands, and GI tract. It is activated by THC and some endocannabinoids but is structurally distinct from CB1 and CB2. CBD acts as a GPR55 antagonist, which may contribute to its anticonvulsant effects — GPR55 activation promotes neuronal excitability. GPR55 is also expressed in cancer cells and may play a role in tumor growth, making it a potential oncology target.
Related Terms
More in Pharmacology
Endocannabinoid System (ECS)
A lipid-based retrograde neurotransmitter system comprising endogenous cannabinoids (endocannabinoids), their receptors (CB1, CB2), and metabolic enzymes.
CB1 Receptor
Cannabinoid receptor type 1. A G protein-coupled receptor (GPCR) primarily expressed in the central nervous system. The primary target of THC's psychoactive effects.
CB2 Receptor
Cannabinoid receptor type 2. A GPCR primarily expressed in immune tissues and peripheral organs. Less abundant in the CNS than CB1.
Anandamide (AEA)
N-arachidonoylethanolamine. The first endocannabinoid identified. A partial agonist at CB1 and CB2 receptors, named from the Sanskrit word "ananda" meaning bliss.
2-Arachidonoylglycerol (2-AG)
The most abundant endocannabinoid in the brain. A full agonist at both CB1 and CB2 receptors.