Analysis of an ascidian integrin provides new insight into early evolution of collagen recognition

Abstract

AlphaI domain integrins have been found in the ascidian Ciona intestinalis. We produced Ciona alpha1I domain as a recombinant protein. It did not recognize fibril-forming collagens or bind to GFOGER or other similar motifs in triple-helical peptides. No GFOGER motifs were found in Ciona collagens. As Ciona alpha1I bound to collagen IX, we propose that before the emergence of GFOGER-dependent collagen receptors in vertebrates, alphaI domain integrins might have been able to bind to collagen with alternative mechanisms.