LAMININ E8 ALVEOLARIZATION SITE - HEPARIN SENSITIVITY, CELL-SURFACE RECEPTORS, AND ROLE IN CELL SPREADING

Cell adhesion to amino acids 2179-2198 (SN-peptide) of the laminin-1 a lpha 1-chain is required for lung alveolar formation in vitro (M. L. M atter and G. W. Laurie. J. Cell Biol. 124: 1083-1090, 1994). The natur e of the SN-peptide receptor(s) was probed with neutralizing anti-inte grin monoclonal antibodies (MAb), cells lacking integrin subunits, sol uble heparin, and SN-peptide columns. Cell adhesion and spreading stud ies confirmed the specificity of SN-peptide and revealed adhesion to b e unaffected by inclusion of anti-beta(1)- anti-alpha(2-6)- or anti-al pha(V) beta(5)-integrin MAb. Cells lacking beta(1)- or alpha(6)-integr in subunits were fully adherent. Adhesion was heparin, but not chondro itin sulfate or heparinase, sensitive, much as is alpha-dystroglycan-l aminin-1 binding. Heparin eluted similar to 155- and 180-kDa cell-surf ace proteins from SN-peptide columns. An additional similar to 91-kDa protein was eluted by EDTA. All were unrecognized by anti-beta(1)-inte grin MAb. SN-peptide therefore interacts with three cell-surface prote ins for which the identity remains to be determined.