DETERMINATION OF THE VITRONECTIN BINDING-SITE ON PLASMINOGEN-ACTIVATOR INHIBITOR-1 (PAI-1)

Vitronectin is the carrier protein of plasminogen activator inhibitor 1 (PAI-1). We used a well-characterized panel of anti-human PAI-1 mono clonal antibodies (MoAbs) to localize the vitronectin-binding site on PAI-1. By employing a direct vitronectin/PAI-1 binding assay and two v itronectin-dependent inhibition assays, we demonstrate that the anti-P AI-1 MoAbs CLB-5, CLB-10, CLB-2C8 and 11, directed against different e pitopes in the region between amino acids 110 and 145, prevent the int eraction of PAI-1 with vitronectin. We conclude that the region betwee n amino acids 110 and 145 of PAI-1 harbours an important determinant f or the interaction with vitronectin.