Furin proteolytically processes the heparin-binding region of extracellular superoxide dismutase

J Biol Chem. 2002 May 10;277(19):16505-11. doi: 10.1074/jbc.M105409200. Epub 2002 Feb 22.


Extracellular superoxide dismutase (EC-SOD) is an antioxidant enzyme that attenuates brain and lung injury from oxidative stress. A polybasic region in the carboxyl terminus distinguishes EC-SOD from other superoxide dismutases and determines EC-SOD's tissue half-life and affinity for heparin. There are two types of EC-SOD that differ based on the presence or absence of this heparin-binding region. It has recently been shown that proteolytic removal of the heparin-binding region is an intracellular event (Enghild, J. J., Thogersen, I. B., Oury, T. D., Valnickova, Z., Hojrup, P., and Crapo, J. D. (1999) J. Biol. Chem. 274, 14818-14822). By using mammalian cell lines, we have now determined that removal of the heparin-binding region occurs after passage through the Golgi network but before being secreted into the extracellular space. Specific protease inhibitors and overexpression of intracellular proteases implicate furin as a processing protease. In vitro experiments using furin and purified EC-SOD suggest that furin proteolytically cleaves EC-SOD in the middle of the polybasic region and then requires an additional carboxypeptidase to remove the remaining lysines and arginines. A mutation in Arg(213) renders EC-SOD resistant to furin processing. These results indicate that furin-dependent processing of EC-SOD is important for determining the tissue distribution and half-life of EC-SOD.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Arginine / chemistry
  • Blotting, Western
  • Brefeldin A / pharmacology
  • CHO Cells
  • Cell Line
  • Cricetinae
  • Electrophoresis, Polyacrylamide Gel
  • Enzyme Inhibitors / pharmacology
  • Furin
  • Glycine / chemistry
  • Golgi Apparatus / metabolism*
  • Heparin / chemistry
  • Heparin / metabolism*
  • Humans
  • Mass Spectrometry
  • Mice
  • Molecular Sequence Data
  • Mutation
  • Oxidative Stress
  • Precipitin Tests
  • Protein Binding
  • Protein Structure, Tertiary
  • Protein Synthesis Inhibitors / pharmacology
  • Rats
  • Subtilisins / chemistry
  • Subtilisins / metabolism*
  • Superoxide Dismutase / metabolism*
  • Temperature
  • Time Factors
  • Tissue Distribution
  • Tumor Cells, Cultured


  • Enzyme Inhibitors
  • Protein Synthesis Inhibitors
  • Brefeldin A
  • Heparin
  • Arginine
  • Superoxide Dismutase
  • Subtilisins
  • Furin
  • Glycine