SEP2 and SEP-3 are integral membrane proteins expressed in blood stages and ookinetes.

<p>A) Schematic representation (not drawn to scale) of <i>Pbsep2</i> and <i>Pbsep3</i> loci. B) <i>P. berghei</i> rings (R), trophozoites (T), schizonts (S) and gametocytes (G) were analyzed by western blot using αSEP2 and αSEP3 immune sera. The amount of protein loaded in each lane was assessed by Bradford. C) soluble (S) and insoluble (I) fractions prepared from purified ookinetes were analyzed by western blot using αSEP2 and αSEP3 immune sera. Both proteins are mainly detected in the insoluble fraction. D) Specific antibodies detect SEP2 in dot-like structures inside the ookinete but also close to the parasite periphery, as shown by partial co-localization with the ookinete surface protein P28 (left panel). SEP2 does not co-localize with the micronemal protein SOAP (right panel). A single section (1) and a stack of the same ookinete (2) are shown. The sample was imaged in a DeltaVision Elite deconvolution microscope and one single section through the middle of the ookinete is shown. DNA was labeled with DAPI (blue).