Figure 1.

Direct binding assay and Scatchard analysis of plasminogen and angiostatin with endothelial cells. HUVEC were plated at a density of 10,000 cells/well and incubated with increasing concentrations of ¹²⁵I-labeled-plasminogen or -angiostatin as described in Materials and Methods. (A) ¹²⁵I-labeled plasminogen binding was concentration dependent and saturable with an apparent dissociation constant (K_d) of 158 nM and 870,000 sites/cell. (B) Binding to HUVEC with ¹²⁵I-labeled angiostatin was concentration dependent and saturable with a K_d of 245 nM and 38,000 sites/cell. Error bars represent SD.