Leukotriene B4-3-aminopropylamide (LTB4-APA) is a leukotriene immunomodulator. The study found that LTB4 can bind to the polar carboxylic acid group of LTB4 near the outer surface of BLT1 cells, and the hydrophobic LTB4 tail points to the transmembrane region of the receptor protein^[1].