4.4.1.20 evolution the enzyme belongs to the superfamily of membrane-associated proteins in eicosanoid and glutathione metabolism, which consists of six integral membrane proteins 730061 4.4.1.20 evolution the enzyme belongs to the superfamily of membrane-associated proteins in eicosanoid and glutathione metabolism, which consists of six integral membrane proteins. Although structural differences near the active site and along the C-terminal alpha-helix V suggest that the mouse and human enzymes may function differently in vivo 730788 4.4.1.20 additional information enzyme residue Trp116 is not essential for catalysis but helps position the omega-end of leukotriene A4 730061 4.4.1.20 physiological function A-444C polymorphism on the LTC4S gene is associated with aspirin-induced urticaria. The C allele is more frequent in patients with the cutaneous pattern of aspirin-induced urticaria and in patients with low skin reactivity to histamine. There is no association between A-444C and asthma, atopy, or total IgE levels 709410 4.4.1.20 physiological function GST2 knock-down by specific siRNA significantly depresses LTC4 contents with 27.0 % decrease at 24 h. Reactive oxygen species levels are elevated by 40.1% in vitro. Increased expression of GST2 leads to 1.56fold increase in LTC4 synthase activity 748662 4.4.1.20 physiological function in coincubations of platelets and polymorphonuclear leukocytes, inhibition of LTC4S leads to shunting of LTA4 toward anti-inflammatory lipoxin A4, which is significantly enhanced by simultaneous inhibition of LTA4H 748456 4.4.1.20 physiological function leukotrienes are a family of drug-like molecules involved in the pathobiology of bronchial asthma and are responsible for smooth muscle contraction 730555 4.4.1.20 physiological function LTC4S interacts in vitro with both 5-lipoxygenase activating protein and 5-lipoxygenase, these interactions involve distinct parts of LTC4S. 5-lipoxygenase activating protein binds to the N-terminal part/first hydrophobic region of LTC4S, whereas 5-lipoxygenase binds to the second hydrophilic loop of LTC4S. Direct interaction of 5-lipoxygenase and LTC4S in ionophore-stimulated (but not unstimulated) cells 702043 4.4.1.20 physiological function perennial allergic rhinitis biopsies show 3fold more cells immunostaining for LTC4 synthase compared with seasonal allergic rhinitis biopsies but this is not significant compared with normal biopsies, probably because normal biopsies show relatively high variability for LTC4 synthase 708181 4.4.1.20 physiological function the enzyme catalyzes the conjugation reaction between the fatty acid leukotriene A4 and GSH to form the pro-inflammatory leukotriene C4, an important mediator of asthma 730061, 730788