Protease-nexin: a cellular component that links thrombin and plasminogen activator and mediates their binding to cells

Cell. 1980 Aug;21(1):37-45. doi: 10.1016/0092-8674(80)90112-9.


This report identifies a component of normal human fibroblasts that forms a covalent linkage with thrombin and urokinase (urinary plasmingoen activator) and mediates most of the specific cellular binding of these proteases. This component, here named protease-nexin (PN), is both associated with the cell surface and released into the culture medium. In several ways PN resembles antithrombin III (AT3), a prominent inhibitor of thrombin in serum: PN links thrombin, probably via an ester bond; PN does not link thrombin blocked at its catalytic site serine; PN has a high-affinity heparin-binding site; and heparin greatly accelerates the rate of linkage between soluble PN and thrombin. Despite these similarities, PN and AT3 are distinct; they differ in size and are not immunologically cross-reactive. Whereas AT3 regulates the proteolytic activity of thrombin in serum, PN may regulates the activity of serine proteases at and near the cell surface.

Publication types

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

MeSH terms

  • Amyloid beta-Protein Precursor
  • Antithrombin III / immunology
  • Carrier Proteins / immunology
  • Carrier Proteins / physiology*
  • Cell Line
  • Chemical Phenomena
  • Chemistry
  • Endopeptidases / metabolism*
  • Epitopes
  • Fibroblasts
  • Heparin / metabolism
  • Humans
  • Male
  • Plasminogen Activators / metabolism*
  • Protease Nexins
  • Receptors, Cell Surface
  • Thrombin / metabolism*
  • Urokinase-Type Plasminogen Activator / metabolism*


  • Amyloid beta-Protein Precursor
  • Carrier Proteins
  • Epitopes
  • Protease Nexins
  • Receptors, Cell Surface
  • Antithrombin III
  • Heparin
  • Endopeptidases
  • Plasminogen Activators
  • Thrombin
  • Urokinase-Type Plasminogen Activator