PEPTIDE SEQUENCES SELECTED BY BA4, A TROPOELASTIN-SPECIFIC MONOCLONAL-ANTIBODY, ARE LIGANDS FOR THE 67-KILODALTON BOVINE ELASTIN RECEPTOR

A 67-kDa cell-surface elastin/laminin receptor is expressed by fetal bovine ligamentum nuchae fibroblasts and neutrophils. Two hexapeptides, VGVAPG and PGAIPG, contained within hydrophobic domains of tropoelastin are binding sites for this receptor. Studies of recombinant tropoelastin proteins and synthetic peptides demonstrated that a monoclonal antibody, BA4, recognized peptide sequences similar to those recognized by the 67-kDa receptor. Taking advantage of this similarity, an ''epitope library'' containing random hexapeptides was screened with BA4. Four BA4-selected peptides (VGAMPG, VGMAPG, VGSLPG, and VGLSPG) were synthesized; studies of fibroblast and neutrophil migration support the hypothesis that these peptides are ligands of the 67-kDa receptor present on ligamentum nuchae fibroblasts and neutrophils. Two additional, physically similar tropoelastin peptides, AGAIPG and PGAVGP, were also identified as peptide ligands, and hence potential binding sites within tropoelastin, of the elastin receptor. These data suggest that the 67-kDa elastin/laminin receptor may interact with a wide range of structurally similar peptides containing amino acid substitutions involving small nonpolar and uncharged amino acids.