Heterodimer formation is essential for heparanase enzymatic activity

Biochem Biophys Res Commun. 2003 Sep 5;308(4):885-91. doi: 10.1016/s0006-291x(03)01478-5.


Heparanase is an endo-beta-D-glucuronidase involved in cleavage of heparan sulfate residues and hence participates in extracellular matrix degradation and remodeling. The heparanase cDNA encodes for a polypeptide of 543 amino acids that appears as a approximately 65 kDa band in SDS-PAGE analysis. The protein undergoes a proteolytic cleavage that is likely to occur at two potential cleavage sites, Glu(109)-Ser(110) and Gln(157)-Lys(158), yielding an 8 kDa polypeptide at the N-terminus, a 50 kDa polypeptide at the C-terminus, and a 6 kDa linker polypeptide that resides in-between. The active form of heparanase has long been thought to be a 50 kDa polypeptide isolated from cells and tissues. However, attempts to obtain heparanase activity after expression of the 50 kDa polypeptide failed, suggesting that the N-terminal region is important for heparanase enzymatic activity. It has been hypothesized that heterodimer formation between the 8 and 50 kDa heparanase subunits is important for heparanase enzymatic activity. By individually or co-expressing the 8 and 50 kDa heparanase subunits in mammalian cells, we demonstrate specific association between the heparanase subunits by means of co-immunoprecipitation and pull-down experiments. Moreover, a region in the 50 kDa heparanase subunit that mediates interaction with the 8 kDa subunit was identified. Altogether, our results clearly indicate that heterodimer formation is necessary and sufficient for heparanase enzymatic activity in mammalian cells.

Publication types

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

MeSH terms

  • Amino Acids / chemistry
  • Binding Sites
  • Blotting, Western
  • Cell Line
  • Cloning, Molecular
  • DNA, Complementary / metabolism
  • Dimerization
  • Electrophoresis, Polyacrylamide Gel
  • Glucuronidase / chemistry
  • Glucuronidase / metabolism*
  • Glutathione Transferase / metabolism
  • Heparitin Sulfate / chemistry
  • Humans
  • Immunoblotting
  • Peptides / chemistry
  • Plasmids / metabolism
  • Precipitin Tests
  • Protein Structure, Tertiary
  • Transfection
  • Tumor Cells, Cultured


  • Amino Acids
  • DNA, Complementary
  • Peptides
  • Heparitin Sulfate
  • Glutathione Transferase
  • heparanase
  • Glucuronidase