May be involved in hyperalgesia associated with inflammatory and neuropathic pain (By similarity). Receptor for L-alpha-lysophosphatidylinositol (LPI). LPI induces Ca(2+) release from intracellular stores via the heterotrimeric G protein GNA13 and RHOA. Putative cannabinoid receptor. May play a role in bone physiology by regulating osteoclast number and function. Expressed in the caudate nucleus and putamen, but not detected in the hippocampus, thalamus, pons cerebellum, frontal cortex of the brain or in the liver. Expressed in osteoclasts and osteoblasts. The classification of this protein as a cannabinoid receptor remains a contentious issue due to conflicting pharmacological results. Belongs to the G-protein coupled receptor 1 family.