Fig. 3. Cellular distribution of EhPAK and F-actin in a motile E. histolytica. Amoeba moving from left to right display a prominent pseudopod that guides its locomotion. After fixation and permeabilisation, filamentous actin was decorated with FITC-phallacidine (green), and EhPAK was stained with purified polyclonal antibodies against EhPAK (red). A confocal micrograph of an optical plane in the middle of the parasite showed that F-actin was moderately concentrated in the pseudopod, distributed in the cytoplasm and enriched at the posterior end of the parasite. EhPAK was dispersed throughout the cytoplasm and was concentrated in pseudopodia extensions. Superimposition of the two stainings indicates that F-actin and EhPAK were concentrated at specific opposite sites of the parasite. The differential interference contrast (DIC) image shows E. histolytica with a pseudopod at the front of migration. Bar, 5 µm.