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Localization of protease nexin‐1 on the fibroblast extracellular matrix

Localization of protease nexin‐1 on the fibroblast extracellular matrix 10.1002/jcp.1041340203.abs 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. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Journal of Cellular Physiology Wiley

Localization of protease nexin‐1 on the fibroblast extracellular matrix

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References (26)

Publisher
Wiley
Copyright
Copyright © 1988 Wiley‐Liss, Inc.
ISSN
0021-9541
eISSN
1097-4652
DOI
10.1002/jcp.1041340203
pmid
3279057
Publisher site
See Article on Publisher Site

Abstract

10.1002/jcp.1041340203.abs 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.

Journal

Journal of Cellular PhysiologyWiley

Published: Feb 1, 1988

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