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Erythrocyte invasion by the blood-stage Plasmodium falciparum parasites is a multistep process involving specific interactions between parasites and red blood cells. Several proteins are involved in this process, including EBL ligands. The structure of the EBA-140 ligand, a member of the EBL protein family, provides a full description of its molecular interactions with the erythrocyte receptor. The crystal structure of the EBA-140 Region II in a complex with sialolactose revealed that the binding region is monomeric. Two glycan binding pockets, one in each F1 or F2 domain, were identified. Stark differences in the receptor binding for the F1 and F2 domains suggests that each domain performs a distinct function. Although both domains are required for effective glycan binding, it seems that the interaction may be mediated solely by the F1 domain. The structure of the binding region and the interaction with glycan are unique to the EBA-140 ligand and not shared by other EBL ligands. The EBA-140 ligand binds specifically to human erythrocytes through the membrane sialoglycoprotein glycophorin C. The receptor site for the EBA-140 ligand was suggested to be a cluster of N-and O-linked sialylated glycans on the GPC molecule, whose conformation is dependent on the polypeptide chain region composed of amino acid residues 36-63. Precise definition of the binding site for the EBA-140 ligand on glycophorin C may be important with respect to human erythrocyte invasion inhibition strategies based on a receptor.

The article presents the current knowledge on the proteines under question. The first analysed E-S products released by G. duodenalis was a polydisperse hydrophobic complex (16.5-225 kDa), protease VI sensitive, chloroform-methanol insoluble. Based on inhibition studies cysteine protease and metalloprotease were detected in the complex. The further analysis revealed that a 58 kDa heat stable as wall as protease sensitive glycoprotein secreted by G. duodenalis trophozoites is highly immunogenic for the hosts. Before encystation, G. duodenalis trophozoites secrete leucine-rich cyst wall proteins: CWP1, CWP2 and CWP3. Steady-state levels of CWPs gene transcripts are low in non-encysting trophozoites but increase more than 100-fold during encystation. Another protein, which expression also increases during encystation is gGSP (Giardia Granule-Specific Protein). The protein possesses typical strucutre of calcium-binding proteins. Inhibition of gGSP expression abolishes cyst wall formation, suggesting that this protein regulates Ca(2+)-dependent degranulation of encystation-specific secretory vesicles (ESVs) during cyst wall formation.

The article is based on newly published data concerning cell structure (cytoskeleton and cytoplasmic organelle) and biochemistry of the protozoon Toxoplasma gondii, many of which can be applied in therapy of toxoplasmosis.

The article presents data concerning methods of proteomics and main achievements of studies on Toxoplasma gondii proteom.

The article presents selected data concerning invasion and intracellular life of obligate intracellular parasite Toxoplasma gondii in susceptible hosts.