FIGURE 1.

Three-dimensional structure of uPA. A, overview of the three-dimensional structure of the serine protease domain of active uPA, displayed as ribbons. Depicted as sticks are the residues Ile¹⁶, Asp¹⁹⁴, and Ser¹⁹⁵. The activation domain, i.e. the activation loop (residues 16-21), the autolysis loop (residues 142-152), the oxyanion stabilizing loop (residues 184-193), and the S1 entrance frame (residues 216-223) are colored green. B, the epitope of mAb-112, displayed on a surface presentation of the serine protease domain of active uPA. Alanine substitution of residues depicted in red resulted in a significant change in the affinity to mAb-112, whereas alanine substitution of residues depicted in blue did not. C, a close up view of the autolysis loop (residues Gly¹⁴¹ to Lys¹⁵⁶) and residues implicated in the binding of mAb-112. All figures were constructed with Pymol on the basis of the coordinates given in the PDB entry 1C5W.