Objective   To identify the binding motif of alphavbeta3 integrin in human laminin alpha 4 subunit (LNα4).    Methods   The conserved amino acid residues were determined by blast analysis based on G19 peptide sequence (G

1121-1139

). The key sites were identified by single-site mutant and the binding motif was identified by deletion mutant. The function of identified motif was analyzed by tubelike structure formation of human umbilical vein endothelial cells (HUVECs) in vitro and angiogenesis assay on chick chorioallantoic membrane in vivo

.    Results   Total 10 conserved amino acid residues were found in G19 peptide through blast analysis

and 3 key sites binding with alphavbeta3 integrin were identified by single-site mutant. The shortest fragment between G

1124-1137

was identified by deletion mutant and fragment promoted tube-like structure formation by hUVECs and angiogenesis on CAM in a dose-dependent manner.    Conclusion   The key sites and the shortest fragment binding with alphavbeta3 integrin in LNα4 are identified successfully

which provides the evidence for the function of LNα4 in illness.