Different mAbs bind to different regions of VE-cadherin.

(A) Schematic representation of VE-cadherin fragments spanning different regions of the protein ectodomain and the mAb binding domain. TM indicates transmembrane domain; EC, extracellular domain. (B) Western blot analysis of mAbs binding to VE-cadherin fragments produced in Escherichia coli. Antihistidine antibody recognized the 3 fragments VE1, VE2, and VE3, which migrated at molecular weights of 60, 40, and 30 kd, respectively. Monoclonal antibodies TEA 1.31 and BV6 bound to VE1 and VE3 but not VE2. mAb Cad 5 bound to VE1 and VE2. (C) Immunoprecipitation analysis of VE3 and VE4 obtained by protein synthesis in vitro. Biotinylated lysine residues are incorporated into nascent proteins during translation. Fragments VE3 and VE4 were immunoprecipitated with Cad 5, BV6, and BV9, and after sodium dodecyl sulfate–polyacrylamide gel electrophoresis and electroblotting, the biotinylated proteins were visualized by streptavidin–horseradish peroxidase. Cad 5 bound to VE4 while BV6 and BV9 bound to VE3 only.