Processing of PfCnA in vivo and in vitro. Immunoblot analysis was performed with peptide antibodies CnA-1, -2 and -3 (described in Fig. 1) and with the anti-His tag antibody. The lanes contained the following samples: 1 = 50 μg total protein from freshly isolated parasite; 2 = same as 1 except that the parasite was incubated at room temperature for 5 min; 3 = 120 ng of purified His-tagged (recombinant) PfCnA; 4 = as in lane 3 but following incubation with parasite extract; 5 = as in lane 4 except that the incubation mixture also contained protease inhibitor cocktail. In the right panel (Stain) higher quantities (5 μg) of the same recombinant protein samples of the corresponding lane numbers were analyzed and the gel stained with Coomassie Blue R250. The full-length and processed bands are indicated as F and P, respectively. Size markers are indicated on the two sides. Details are given in Methods.