FIGURE 4.

PAI-1 does not form complexes with single-chain FSAP.A, complexes between PAI-1 (applied at different concentrations) and scFSAP were formed for 30 min, and samples were analyzed by SDS-PAGE under nonreducing conditions, followed by Western blot analysis with a FSAP-specific antibody (top) and a PAI-1-specific antibody (bottom). B, binding of PAI-1 in the absence (▪) or presence (•) of a rabbit anti-FSAP antibody or of preformed PAI-1-uPA complexes (▴) to immobilized scFSAP was performed in microtiter plates, and bound PAI-1 was quantified with a rabbit polyclonal antibody directed against PAI-1. Inset, autoconversion of scFSAP to tcFSAP (indicated by the appearance of the FSAP heavy chain (hcFSAP)) after a 16-h incubation at 4 °C. Data represent the mean ± S.D. (n = 5) of a single representative experiment of three independent experiments.