Monocyte-derived soluble protein confers 5-lipoxygenase activity Ca2+-dependent

Biochem Biophys Res Commun. 2002 Jul 26;295(4):985-91. doi: 10.1016/s0006-291x(02)00791-x.


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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Arachidonate 5-Lipoxygenase / metabolism*
  • Arachidonic Acid / metabolism
  • Arachidonic Acid / pharmacology
  • Calcium / metabolism*
  • Catalysis
  • Cells, Cultured
  • Dose-Response Relationship, Drug
  • Humans
  • Ionomycin / pharmacology
  • Ionophores / pharmacology
  • Leukotrienes / metabolism
  • Monocytes / metabolism*
  • Neutrophils / metabolism
  • Phosphatidylcholines / metabolism
  • Protein Binding
  • Rats


  • Ionophores
  • Leukotrienes
  • Phosphatidylcholines
  • Arachidonic Acid
  • Ionomycin
  • Arachidonate 5-Lipoxygenase
  • Calcium