Binding of Tenascin-C to Soluble Fibronectin and Matrix Fibrils *
- From the Department of Cell Biology, Duke University Medical Center, Durham, North Carolina 27710
- Laboratory of Cell Biology, Istituto Nazionale per la Ricerca sul Cancro, Viale Benedetto XV, 10, 16132 Genoa, Italy
- § To whom correspondence should be addressed: Dept. of Cell Biology, Rm. 365, Sands Bldg., Duke University Medical Center, Research Dr., Durham, NC 27710. Tel.: 919-684-6385; Fax: 919-684-3687; Harold_Erickson{at}cellbio.duke.edu.
Abstract
The small splice variant of tenascin-C (TN) has eight fibronectin type III (FN3) domains. The major large splice variant has three (in chicken) or seven (in human) additional FN3 domains inserted between domains five and six. Chiquet-Ehrismann et al. (Chiquet-Ehrismann, R., Matsuoka, Y., Hofer, U., Spring, J., Bernasconi, C., and Chiquet, M. (1991, Cell Regul. 2, 927-938) demonstrated that the small variant bound preferentially to fibronectin in enzyme-linked immunosorbent assay, and only the small variant was incorporated into the matrix by cultures of chicken fibroblasts. Here we have studied human TN, and confirmed that the small variant binds preferentially to purified fibronectin and to fibronectin-containing extracellular matrix. Thus this differential binding appears to be conserved across vertebrate species. Using bacterial expression proteins, we mapped the major binding site to the third FN3 domain of TN. Consistent with this mapping, a monoclonal antibody against an epitope in this domain did not stain TN segments bound to cell culture matrix fibrils. The enhanced binding of the small TN variant suggests the existence of another, weak binding site probably in FN3 domains 6-8, which is only positioned to bind fibronectin in the small splice variant. This binding of domains 6-8 may involve a third molecule present in matrix fibrils, as the enhanced binding of small TN was much more prominent to matrix fibrils than to purified fibronectin.
Footnotes
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↵* This work was supported by National Institutes of Health Grant R37 CA47056 (to H. P. E.). The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore by hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
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↵1 The abbreviations used are:
- TN
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tenascin-C
- Ab
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antibody
- ECM
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extracellular matrix
- ELISA
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enzyme-linked immunosorbent assay
- FN
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fibronectin
- FN3
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fibronectin type-III (domains)
- PBS
-
phosphate-buffered saline
- BHK
-
baby hamster kidney
- EGF
-
epidermal growth factor.
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↵2H. P. Erickson, unpublished data.
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- Received July 5, 1995.
- Revision received August 23, 1995.
- © 1995 by The American Society for Biochemistry and Molecular Biology, Inc.
