Monocyte-derived soluble protein confers 5-lipoxygenase activity Ca2+-dependent.
5-Lipoxygenase (5-LO) is a Ca2+-stimulated enzyme that initializes the formation of proinflammatory leukotrienes from arachidonic acid (AA). In this report, we demonstrate that a soluble protein of the monocytic cell line Mono Mac 6 confers 5-LO activity Ca2+-dependent in vitro. Thus, in broken cell preparations of human polymorphonuclear leukocytes (PMNL) and rat basophilic leukemia (RBL)-1 cells, 5-LO converted AA (>20 microM) in the absence of Ca2+, whereas Ca2+ was absolutely required for 5-LO activity in broken cell preparations of MM6 cells. 5-LO partially purified from MM6 cells was substantially active in the absence of Ca2+. Recombination experiments revealed that the cytosolic fraction of MM6 cells contains a factor that suppresses the activity of partially purified 5-LO from PMNL, RBL-1, and MM6 cells in the absence but not in the presence of Ca2+. Further characterization showed that this factor is a 80-100 kDa heat-sensitive protein.
Institute of Pharmaceutical Chemistry, University of Frankfurt, Frankfurt, Germany.
Eva
E
Bürkert
Olof
O
Rådmark
Dieter
D
Steinhilber
Oliver
O
Werz
D000818:Animals; D001094:Arachidonate 5-Lipoxygenase / Q000378:metabolism*; D016718:Arachidonic Acid / Q000378:metabolism / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D002384:Catalysis; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D006801:Humans; D015759:Ionomycin / Q000494:pharmacology; D007476:Ionophores / Q000494:pharmacology; D015289:Leukotrienes / Q000378:metabolism; D009000:Monocytes / Q000378:metabolism*; D009504:Neutrophils / Q000378:metabolism; D010713:Phosphatidylcholines / Q000378:metabolism; D011485:Protein Binding; D051381:Rats
D007476:Ionophores; D015289:Leukotrienes; D010713:Phosphatidylcholines; D016718:Arachidonic Acid; D015759:Ionomycin; D001094:Arachidonate 5-Lipoxygenase; D002118:Calcium