Disruption of PfSBP1 and expression of PfSBP1 protein in P falciparum. (A) Schematic representation of parental (CS2) and disrupted PfSBP1 loci (CS2ΔSBP1). The WR99210 resistance gene hDHFR was inserted into the PfSBP1 locus by double crossover recombination resulting in the CS2ΔSBP1 parasite line. Restriction sites used for Southern blot analysis and the predicted fragment sizes are shown (B, BglII; E, EcoRI) (B) Southern blot analysis of the PfSBP1 locus in parental CS2 and transgenic CS2ΔSBP1 cell lines. Genomic DNA was digested with EcoRI/BglII and probed with the 5′ (probe A) and 3′ (probe B) targeting sequence. Predicted sizes for the 5′ probe were wild-type, 4.6 kb (kilobase); disrupted loci, 2.7 kb; and plasmid, 6.9 kb; predicted sizes for the 3′ probe were wild-type, 4.6 kb; disrupted loci, 1.1 kb; and plasmid 6.9 kb. (C) Western blot of saponin pellets of trophozoite-infected erythrocytes of CS2 parent and CS2ΔSBP1 probed with anti-SBP1 antibodies. Equal loading of parasite material was confirmed with anti-PfHSP70 antibodies in the bottom panel.