Chinese hamster ovary cell motility to fibronectin is modulated by the second extracellular loop of CD9. Identification of a putative fibronectin binding site.

CD9, a member of the tetraspanin family of proteins, is characterized by four transmembrane domains and two extracellular loops. Surface expression of CD9 on Chinese hamster ovary (CHO) cells dramatically enhances spreading and motility on fibronectin. To elucidate the mechanistic basis of CD9-fibronectin interaction, binding to fibronectin was investigated using purified and recombinant forms of CD9.