Cell binding sequences in mouse laminin alpha 1 chain

Laminin-1, a multifunctional glycoprotein of the basement membrane, consist s of three different subunits, alpha 1, beta 1, and gamma 1 chains. Previou sly, we used synthetic peptides to screen for biologically active sequences in the laminin alpha 1 chain C-terminal globular domain (G domain) and ide ntified several cell binding sequences (Nomizu, M., Kim, W. H., Yamamura, K ., Utani, A., Song, S. Y., Otaka, A., Roller, P. P., Kleinman, H. K., and Y amada, Y. (1995) J. Biol. Chem. 270, 20583-20590). Here, we identify new ce ll binding sequences on the remainder of the laminin alpha 1 chain by syste matic peptide screening, using 208 overlapping synthetic peptides encompass ing the central and N-terminal portions of the alpha 1 chain. HT-1080 cell attachment activity to the peptides was evaluated using peptide-coated plas tic substrates and peptide-conjugated Sepharose beads. Twenty five peptides showed cell attachment activities on either the peptide-coated plastic sub strates and/or the peptide-conjugated Sepharose beads. A-13 (RQVFQVAYIIIKA) showed strongest cell attachment activity in both the assays. Cell attachm ent to 14 of the peptides was inhibited by heparin. EDTA and integrin antib odies inhibited cell adhesion to two of the peptides, A-13 and A-25, sugges ting that these sites likely bind to integrins. These peptides inhibited ce ll attachment to laminin-l but not to collagen I, suggesting these active s ites are available on the intact molecule. Most of active sequences were lo calized on globular domains suggesting that these structures play a critica l role in binding to cell-surface receptors.