title: Molecular characterisation of an expressed sequence tag locus of Toxoplasma gondii encoding the micronemal protein MIC2.
abstract: The expressed sequence tag (EST) dataset of Toxoplasma gondii provides a wealth of information towards gene discovery. The complete cDNA and genomic sequence of EST tgc050 locus shows that it contains five copies of the conserved thrombospondin (TSP)-like motif present in a number of molecules with adhesive properties. A conserved region implicated with the adhesive characteristic of another group of proteins including several integrins, is also present in this molecule. The protein encoded by this sequence (rc50) is strongly recognised by monoclonal antibodies to MIC2. Affinity purified anti-rc50 antisera specifically reacted with a single protein of identical molecular mass as MIC2 and exclusively labeled the micronemes of T. gondii by cryo-immunoelectron microscopy. These results demonstrate that c50 encodes for MIC2, a previously characterised microneme protein of T. gondii. The extensive sequence similarity across multiple protein domains provides evidence that the protein encoded by this locus is the homologue to the Etp100 microneme protein of Eimeria tenella.
authors.affiliation: Department of Pathology, University of Cambridge, UK.
authors.forename: K L
authors.initials: KL
authors.lastname: Wan
authors.forename: V B
authors.initials: VB
authors.lastname: Carruthers
authors.forename: L D
authors.initials: LD
authors.lastname: Sibley
authors.forename: J W
authors.initials: JW
authors.lastname: Ajioka
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D020126:Brefeldin A; D003001:Cloning, Molecular; D003517:Cyclopentanes / Q000494:pharmacology; D018076:DNA, Complementary / Q000235:genetics; D016054:DNA, Protozoan / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics; D015870:Gene Expression / Q000187:drug effects; D017125:Genes, Protozoan; D008565:Membrane Proteins; D016253:Microscopy, Immunoelectron; D008969:Molecular Sequence Data; D015800:Protozoan Proteins / Q000096:biosynthesis / Q000235:genetics* / Q000276:immunology; D011994:Recombinant Proteins / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D014122:Toxoplasma / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism
chemical_list: D003517:Cyclopentanes; D018076:DNA, Complementary; D016054:DNA, Protozoan; C408878:MIC2 protein, Toxoplasma gondii; D008565:Membrane Proteins; D015800:Protozoan Proteins; D011994:Recombinant Proteins; D020126:Brefeldin A