The Pf 3D7 genome [10] was used for the bioinformatics analysis. The generalized sequence profile method and the pftools package [11] were used to search for the short a-helical coiled coil domains. The coiled coil profiles were constructed using an alignment of several amino acid sequences corresponding to the known coiled coil domain. Two profiles containing four and five heptad repeats were used for the analysis. The cut-off levels of the profiles were chosen by tests performed against sequence database of proteins with the known 3D structures. Subsequently, the coiled coil Figure 1 . Immunofluorescence microscopy analysis of Pf 3D7 parasites with peptide specific antibodies. Acetone/methanol-fixed schizonts and merozoites were reacted with A: human peptide specific, affinity purified antibodies obtained with peptides 12 and 14 (Table 1) and B: sera from mice immunized with peptide 27 (Table 1) . Grey: bright field images; blue staining: indicates DAPI nuclear staining of schizont stage parasites; red staining shows labeling of peptide specific antibodies by Cy3-conjugated anti-human or anti-mouse IgG specific antibody. Merge picture is an overlay of the blue and red fluorescence channel. doi:10.1371/journal.pone.0000645.g001 regions selected by this approach were tested manually for the presence of the characteristic heptad repeats. These proteins were also analyzed by the COILS program [25] .