Redistribution of 5-lipoxygenase and cytosolic phospholipase A2 to the nuclear fraction upon macrophage activation.

Both the cytosolic phospholipase A2 and 5-lipoxygenase enzymes redistribute from the high-speed supernatant to a particulate fraction upon cell activation with associated leukotriene synthesis, but the subcellular site to which these enzymes translocate is not known. In this study, we disrupted resting and ionophore A23187-stimulated rat peritoneal macrophages by N2 cavitation and separated lysates into nuclear, cytosolic, and crude membrane fractions; these were then examined by immunoblot analysis for their contents of immunoreactive cytosolic phospholipase A2, 5-lipoxygenase, and 5-lipoxygenase activating protein. 5-Lipoxygenase activating protein was localized predominantly in the nuclear fraction of both resting and activated cells, while both cytosolic phospholipase A2 and 5-lipoxygenase redistributed from the cytosol fraction in resting cells to the nuclear fraction in activated cells. These data demonstrate for the first time coordinate subcellular localization of the key proteins involved in leukotriene synthesis from endogenous arachidonate.