Optimization of the components of the TUBE-DELFIA assay. X axis of panels A and C are represented in logarithmic scale. A. Titration of TUBEs with saturating concentration of proteins from isolated P. falciparum cell extracts (10 μg), using anti-ubiquitin FK2 and europium antibodies at 1:200 dilution. B. TUBE-DELFIA assay using a saturating concentration of proteins from isolated P. falciparum cell extracts (10 μg), 30 ng TUBEs and three different concentrations of anti-ubiquitin FK2 and secondary europium antibodies. A control without proteins was used to determine the background signal. C. Haematocrit titration of iRBCs with schizonts at 100% parasitaemia treated with MG132 inhibitor (1.5 μM), using the conditions previously established (30 ng TUBEs, 1:100 FK2 and 1:200 europium antibodies).