Colocalization of tPA-GFP with fibrin protein aggregates. Orange-labeled fibrinogen was clotted with thrombin at 5nM (A-C, fibrin₅) or 100nM (D-F, fibrin₁₀₀) and fibrinolysis initiated with the addition of tPA-GFP. After 35 minutes of lysis, micrographs were taken of green fluorescence (A,D) and red fluorescence (B,E). (C,F) Overlays of the corresponding single fluorescent micrographs for each fibrin type. Fibrin₅ shows the granular pattern of fibrin aggregates noted previously, which can be seen to bind tPA. (C) Overlay also shows a number of green particles of precipitated tPA-GFP. Fibrin₁₀₀ displays a narrow zone of bound tPA and few fibrin aggregates.