More than 30 lipid ligands, which express their biological activities through cognate G-protein-coupled receptors (GPCRs), have been reported. Among them, leukotriene B4 (LTB4) is a potent lipid mediator involved in host defense, inflammation, and the immune responses. Two GPCRs for LTB4 (BLT1 and BLT2) have been cloned and analyzed. Recent studies using genetically engineered mice suggest that BLT1 plays an important role in several inflammatory diseases including ischemic reperfusion tissue injury, atherosclerosis, and bronchial asthma. BLT1 is also a good tool to study the molecular mechanism of GPCR activation and inactivation in vitro. In this brief review, we focus on the biological and biochemical properties of BLT1 with special attention to the putative helix 8 of the receptor.
