Prostatic kallikrein hK2, but not prostate-specific antigen (hK3), activates single-chain urokinase-type plasminogen activator

Int J Cancer. 1997 May 29;71(5):897-9. doi: 10.1002/(sici)1097-0215(19970529)71:5<897::aid-ijc31>;2-2.


Our work was undertaken to compare the relative efficiency of 2 purified prostatic kallikreins, namely, hK2 and prostate-specific antigen (PSA or hK3), in the activation of single-chain urokinase (scuPA). We found that hK2 converts scuPA into an active enzyme with an efficiency equal to approximately 1/50 that of plasmin. During the activation of scuPA by hK2, two fragments of 33 and 22 kDa were generated. The NH2-terminal amino acid sequence of the 33 kDa fragment showed that hK2 cleaved scuPA between Lys158 and Ile159. In contrast to a previous report by another group, our purified hK3 preparation containing no trypsin-like contaminants was totally unable to activate scuPA. Our results show that kallikrein hK2 has plasmin-like activity and suggest that it could be the initiator of a proteolytic cascade leading to prostatic cancer invasion.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Enzyme Activation / drug effects
  • Fibrinolysin / metabolism
  • Humans
  • Hydrolysis
  • Kallikreins / isolation & purification
  • Kallikreins / metabolism
  • Kallikreins / pharmacology*
  • Male
  • Molecular Sequence Data
  • Peptide Fragments / chemistry
  • Peptide Fragments / metabolism
  • Plasminogen / metabolism
  • Prostate / enzymology*
  • Urokinase-Type Plasminogen Activator / chemistry
  • Urokinase-Type Plasminogen Activator / metabolism*


  • Peptide Fragments
  • Plasminogen
  • Kallikreins
  • Fibrinolysin
  • Urokinase-Type Plasminogen Activator