THE BINDING OF LEUKOTRIENE BIOSYNTHESIS INHIBITORS TO SITE-DIRECTED MUTANTS OF HUMAN 5-LIPOXYGENASE-ACTIVATING PROTEIN

Site-directed mutagenesis was used to develop deletion and point mutan ts of human 5-lipoxygenase-activating protein (FLAP), which were then expressed in COS-7 cells. Membrane preparations from these cells were analyzed in a radioligand binding assay. Binding of leukotriene biosyn thesis inhibitors to FLAP mutants containing deletions of 2 to 6 amino acids within the region from residue 48-61 was undetectable. This fin ding is consistent with previous studies which suggest that residues a mino-terminal to the proposed second transmembrane of FLAP are critica l for inhibitor binding. The present study also defines residues of FL AP a) amino-terminal to residue 48, b) between the proposed second and third transmembrane regions and c) in the C-terminal region of the pr otein which are not involved in inhibitor binding.