抄録
Confluent monolayers of cultured bovine aortic endothelial cells (BAEC) at 4°C bound specifically, saturably, and with high affinity radioiodinated bovine serum albumin ([125I] -BSA). Unlike bovine transferrin, fibrinogen, and immunoglobulin G, albumin significantly displaced [125I] -BSA binding to the cell surface; 50% inhibition was reached at 15 nM of unlabeled albumin. Binding was reversible, and 45% of the surface associated radioactivity was lost after 2.5 min. The binding data calculated from Scatchard plots were consistent with a single saturable interaction of high affinity with a Kd of 1.6 pmoles, and a Bmax of 45 fmoles/2.5 ×105 cells. The interaction was pH-dependent with an optimum at pH 6.0. Binding was diminished 40% by heparin, 25% by 1 M NaCl but was not markedly affected by cell surface treatment with hyaluronidase and chondroitinase-ABC. Ligand blotting experiments performed with [125I] -BSA showed that extracts of BAEC expressed two albumin binding peptides of apparent molecular mass of 18 and 31 kDa. The albumin binding to BAEC surface was also demonstrated immunohistochemically.
