GRGDS forms the cell-binding domain of the glycoprotein osteopontin (OPN). Although the natural form of OPN is active in cell attachment assays, it has been observed that cleavage of OPN by thrombin results in a significant improvement in its attachment properties. This cleavage occurs within residues of the GRGDS sequence and increases the possibility of thrombin cleavage to further activate OPN by allowing greater accessibility of the GRGDS domain to cell surface receptors. The GRGDS synthetic peptide also mimics the cell binding sites of many adhesion proteins in the extracellular matrix and causes the rounding and detachment of spreading cells. It induces the dissociation of α-actin and vinculin from the focal contact site.
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