The LG3 module of laminin-5 harbors a binding site for integrin alpha(3)beta(1) that promotes cell adhesion, spreading, and migration

Laminins are a family of extracellular matrix glycoproteins involved in cel l adhesion and migration. A major obstacle to understanding their structure -function relationships is the lack of small laminin domains capable of rep licating integrin-binding, cell-adhesive, and migratory functions of the in tact molecule. Here, we show that the recombinant LG3 (rLG3) module (26 kDa ) of laminin-5 (Ln-5) alpha (3) chain replicated key Ln-5 activities. rLG3 but not rLG1 or rLG2 supported cell adhesion and migration of at least two distinct cell lines, in an integrin alpha (3)beta (1)-dependent manner. Cel l adhesion to rLG3 was regulated by divalent cations and accompanied by cel l spreading and tyrosine phosphorylation of FAK focal adhesion kinase. The integrin binding activity of rLG3 was confirmed by rLG3 affinity chromatogr aphy of detergent cell lysates, which resulted in specific purification of integrin alpha (3)beta (1). To our knowledge, this is the first report dire ctly demonstrating that a recombinant laminin LG module is an active domain capable of supporting integrin-dependent cell adhesion and migration.