THE CELL ATTACHMENT AND SPREADING ACTIVITY OF VITRONECTIN IS DEPENDENT ON THE ARG-GLY-ASP SEQUENCE - ANALYSIS BY CONSTRUCTION OF RGD AND DOMAIN DELETION MUTANTS

The cell attachment activity of vitronectin has been ascribed to an Arg- Gly-Asp (RGD) sequence near the amino terminus. To verify the importance of the RGD sequence for cell binding, we created RAD and RGE vitronectin mutants and also deleted either the somatomedin B (ΔS-rVN) or heparin (ΔH-rVN) binding domains. These mutants were expressed as fusion proteins, purified using Ni+2 affinity chromatography, and assayed for cell attachment. EAhy.926 cells bound equally well to wild-type, ΔS-rVN, and to ΔH-rVN, but binding to RAD-rVN and RGE-rVN was inhibited by more than 90%. We therefore conclude that the RGD sequence of vitronectin is the most important cell recognition site and that neither the somatomedin B nor heparin domains contribute significantly to the cell adhesive activity of vitronectin. © 1993 Academic Press, Inc.