Leukotriene B4 receptor 1 (LTB4R1), also designated P2Y purinoceptor 7, is a receptor for extracellular ATP, UTP and ADP. ThrougHuman, Mouseodulation of L-type calcium currents, LTB4-R1 is involved in the regulation of cardiac muscle contraction. It is also a receptor for leukotriene B4 (LTB4), a potent chemoattractant involved in inflammation and immumne response. Leukotriene B4 receptor 2 (LTB4R2) is a ubiquitously expressed 358-amino acid receptor for LTB4.