Protein Domain : Alpha giardin IPR008088

Type	Family
Description	Giardia lamblia (Giardia intestinalis) is a protozoan parasite of numerous mammals, including Homo sapiens []. It belongs to the phylum Sarcomastigophora, and is amongst the most primitive eukaryotes identified to date. It is the main causative agent of global protozoan diarrhoea, and severe infection can cause giardiasis.G. lamblia exists as either trophozoites that live in the small intestine of the host and cause the disease symptoms, or cysts that are passed in thefaeces of the host and infect the next host through contaminated water or food []. Trophozoites exhibit antigenic variation to evade the host immune system, expressing a number of virulence factors to aid adherence and invasion of the small intestine endothelium []. The molecular basis for its antigenic variation has been well characterised, and it is believed that its phenotypic heretogeneity arises from sexual reproduction []. One of themajor virulence factors of G. lamblia is giardin, an antigen expressed as several variants on the trophozoite surface []. Alpha giardin is the predominant immunotypic giardin present, although beta and gamma giardin have also been identified []. This entry represents a family of alpha giardin proteins specific to Giardia. The biochemical properties of the subunit identify the protein as an annexin, a eukaryotic protein widely conservedamongst plants and animals. This protein associates with phosphatidyl serine-containing vesicles in a Ca2+-dependent manner, and has very low sequence similarity with human annexin XIX []. This protein shows a fourfold cyclic configuration of five-helix bundles with repeats I/IV, and II/III each forming a module. The canonical membrane binding site of theannexins is located on the convex side of the molecule [ ].
Short Name	Alpha_giardin