Cell surface molecules that bind fibronectin's matrix assembly domain

A. H. Limper, B. J. Quade, R. M. LaChance, T. M. Birkenmeier, T. S. Rangwala, J. A. McDonald

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Abstract

The assembly of fibronectin into disulfide cross-linked extracellular matrices requires the interaction of mesenchymal cells with two distinct sites on fibronectin, the Arg-Gly-Asp cell adhesive site and an amino-terminal site contained within the first five type I homologous repeats (Quade, B. J., and McDonald, J. A. (1988) J. Biol. Chem. 263, 19602-19609). Proteolytically derived 29-kDa fragments of fibronectin (29kDa) containing these repeats bind to monolayers of cultured fibroblasts and inhibit fibronectin matrix assembly. The cell surface molecules interacting with fibronectin's 29-kDa matrix assembly domain have resisted purification using conventional methods such as affinity chromatography. Accordingly, in order to identify molecules which bind this fragment, 125I-labeled 29kDa was allowed to bind to fibroblast monolayers and chemically cross-linked to the cell surface with bis(sulfosuccinimidyl) suberate. Extraction of the cross-linked cell layer yielded radiolabeled complexes of 56, 150, and 280 kDa. Formation of these cross-linked complexes was specifically inhibited by the addition of excess unlabeled 29kDa but was unaffected by the presence of fibronectin fragments containing other type I repeats outside of the 29kDa matrix assembly domain. The cross-linked complexes were insoluble in nondenaturing detergents but soluble when denatured and reduced, suggesting that 29kDa may be cross-linked to components of the pericellular matrix. Immunoprecipitation of cross-linked cell extracts with a polyclonal antibody to fibronectin that does not recognize the amino terminus demonstrate that the 280-kDa band contains 29kDa cross-linked to fibronectin present on the cell surface. Formation of the 150-kDa complex was inhibited by EDTA, suggesting that divalent cations are required for its formation. Although the molecular mass and divalent cation requirement suggest that the 150-kDa complex may be related to an integrin, this complex was not immunoprecipitated by polyclonal antibodies generated to the α5β1 integrin fibronectin receptor.

Original languageEnglish (US)
Pages (from-to)9697-9702
Number of pages6
JournalJournal of Biological Chemistry
Volume266
Issue number15
StatePublished - Aug 13 1991

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ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

Cite this

Limper, A. H., Quade, B. J., LaChance, R. M., Birkenmeier, T. M., Rangwala, T. S., & McDonald, J. A. (1991). Cell surface molecules that bind fibronectin's matrix assembly domain. Journal of Biological Chemistry, 266(15), 9697-9702.