There are at least four leukotriene receptors. Two receptors have been characterized that bind LTB 4 called BLT 1 and BLT 2 and two receptors that bind the peptidoleukotrienes (cysteinyl leukotrienes) called CysLT1 and CysLT2. The BLT 1 receptor is encoded by the LTB4R gene located on chromosome –q12 and is composed of 3 exons that generates two variant mRNAs that both encode a protein of 352 amino acids. The BLT 2 receptor is encoded by the LTB4R2 gene which is located on chromosome 14q12 and is composed of 2 exons generate two variant mRNAs that both encode a protein of 358 amino acids. The CysLT1 receptor is encoded by the CYSLTR1 gene located on the X chromosome (–) and is composed of 5 exons that generates four variant mRNAs, each of which encode the same 337 amino acid protein. The CysLT2 receptor is encoded by the CYSLTR2 gene located on chromosome and contains a single exon encoding a protein of 346 amino acids.
Falciform ligament – attaches the anterior surface of the liver to the anterior abdominal wall. The free edge of this ligament contains the ligamentum teres, a remnant of the umbilical vein.