THE VLA-2 (ALPHA(2)BETA(1)) I-DOMAIN FUNCTIONS AS A LIGAND-SPECIFIC RECOGNITION SEQUENCE FOR ENDOTHELIAL-CELL ATTACHMENT AND SPREADING - MOLECULAR AND FUNCTIONAL-CHARACTERIZATION

The integrin VLA-2 (alpha(2) beta(1)), generally considered to represe nt the specific collagen receptor on human endothelial cells, contains an alpha(2)-subunit inserted I domain with structural similarity to t he type A domains found within the recently described superfamily of r eceptor-ligand recognition proteins. This region of the cDNA has now b een isolated and used for molecular and functional characterization of this heterodimeric receptor complex. Comparative sequence analysis wi th the porcine homologue revealed 93% amino acid sequence identity, su ggestive of a developmentally conserved function. To complete structur e/function studies, this region of the human cDNA was expressed as a c himeric protein in Escherichia coli, and a rabbit polyclonal antibody (anti-I domain) was used to study determinants of endothelial cell att achment and spreading in vitro. Quantifiable and visual disruption of endothelial cell attachment to gelatin, type I collagen, and laminin w as evident using the specific anti-I domain antibody, with minimal inh ibitory effects demonstrable using fibronectin or fibrinogen matrices. Therefore, these data would suggest that the (alpha(2) beta(1) I doma in confers ligand-binding specificity for both known alpha(2) beta(1) substrates (laminin and collagen), and that this region subserves a re gulatory function in the molecular processes controlling endothelial c ell attachment and spreading in vitro. (C) 1994 by The American Societ y of Hematology.