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Vitronectin's basic domain is a syndecan ligand which functions in trans to regulate vitronectin turnover
Cynthia E Wilkins-Port1, Ralph D Sanderson, Eiman Tominna-Sebald
1Center for Cell Biology and Cancer Research, Neil Hellman Medical Research Building, Albany Medical College, 47 New Scotland Avenue, Albany, NY 12208, USA.
Cell Communication & Adhesion
|December 19, 2003
Summary
Vitronectin (Vn) turnover requires its basic domain to bind syndecans, regulating extracellular matrix proteolysis and cell motility during tissue remodeling. This binding event is crucial for vitronectin degradation.
Area of Science:
- Biochemistry
- Cell Biology
- Extracellular Matrix Biology
Background:
- Vitronectin (Vn) is crucial for tissue remodeling, regulating pericellular proteolysis and cell motility.
- Extracellular Vn levels are controlled by receptor-mediated endocytosis, dependent on binding to sulfated proteoglycans.
Purpose of the Study:
- To identify the specific binding site of vitronectin on syndecans.
- To investigate the role of this binding site in vitronectin turnover and cell adhesion.
Main Methods:
- Preparation of recombinant vitronectins (wild-type and with basic domain deletion) using a baculoviral expression system.
- Assessment of vitronectin binding to cell surfaces and cell adhesion assays using engineered proteins.
- Analysis of vitronectin degradation in the presence of different vitronectin constructs.
Main Results:
- The 12 amino acid basic domain within Vn's heparin-binding domain serves as a syndecan binding site.
- Deletion of the basic domain significantly attenuated Vn binding to cells and cell adhesion.
- The basic domain is essential for vitronectin degradation, and its presence can restore degradation in trans.
Conclusions:
- Vitronectin turnover necessitates the ligation of its basic domain to syndecans.
- Syndecan binding via the basic domain is critical for regulating vitronectin proteolysis and extracellular matrix dynamics.