Molecular design and specific binding of scFv/uPA-T fusion protein to the mouse RBC. (A) Schematic diagram describing the cloning strategy for the fusion construct scFv/uPA-T. The final construct contains a triple FLAG tag at the C-terminus introduced for purification purposes (not shown). (B) Binding of ¹²⁵I-scFv/uPA-T fusion protein to a 1% suspension of washed mouse RBCs. Unless indicated otherwise, data in figures are shown as mean plus or minus SEM (n = 3, deviation bars are smaller than symbols). (C) Mouse RBC agglutination visualized in a V-shaped plate by incubating a 1% suspension of mRBC with indicated concentrations of either monovalent scFv/uPA-T fusion protein or bivalent anti-GPA mAb Ter119. Sharp dots at the bottom of the V-shaped well indicate absence of RBC aggregation. Horizontal lines have been inserted to indicate repositioned images.