Giardia lamblia: Intracellular localization of alpha8-giardin

Alpha8-giardin (a8-giardin) is a member of the multi-gene a-giardin family in the intestinal parasitic protozoan, Giardia lamblia. This gene family shares an ancestry with the annexin super family, whose common characteristic is calcium dependent binding to membranes that contain acidic phospholipids. In the present study, the antigenicity, hydrophilicity, flexibility, surface probability, and secondary structure of a8-giardin amino acids were predicted by bioinformatics applications. A specific anti-peptide antiserum, anti-P3, was used to determine the intracellular location of a8-giardin with confocal immunofluorescence microscopy and immunoelectron microscopy. The results indicated that a8-giardin was located on the plasma membrane and flagella, but not on the ventral disk. Reduction of a8-giardin transcript levels by ribozyme-mediated cleavage decreased trophozoite motility and growth rate, indicating the functional importance of a8-giardin to Giardia trophozoite biology.