Localization of protease nexin‐1 on the fibroblast extracellular matrix

David H. Farrell, Steven L. Wagner, Robert H. Yuan, Dennis D. Cunningham

Research output: Contribution to journalArticlepeer-review

49 Scopus citations


Protease nexin‐1 (PN‐1) is a protease inhibitor that is secreted by fibroblasts and several other cultured cells. PN‐1 forms complexes with certain serine proteases in the extracellular environment including thrombin, urokinase, and plasmin. The complexes then bind to the cells and are rapidly internalized and degraded. This report demonstrates that PN‐1 is present on the surface of fibroblasts, bound to the extracellular matrix. Immunofluorescent studies showed that PN‐1 colocalized with fibronectin on both intact cells and in preparations of extracellular matrix made from these cells. In contrast, PN‐1 did not colocalize with the epidermal growth factor receptor, a plasma membrane marker. An enzyme‐lined immunosorbent assay was developed which showed that the extracellular matrix contained at least 60–80% of the cellular immunoreactive PN‐1. Extraction of the matrix with 2 M NaCl removed PN‐1 in a form which reacted with 125l‐thrombin to form complexes which were immunoprecipitated by anti‐PN‐1 lgG and were of identical size as complexes made from soluble PN‐1 and 125l‐thrombin. These data indicate that in addition to its role as a soluble protease inhibitor, PN‐1 is also a component of the extracellular matrix and might control its proteolysis.

Original languageEnglish (US)
Pages (from-to)179-188
Number of pages10
JournalJournal of Cellular Physiology
Issue number2
StatePublished - Feb 1988
Externally publishedYes

ASJC Scopus subject areas

  • Physiology
  • Clinical Biochemistry
  • Cell Biology


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