Wan K L, Carruthers V B, Sibley L D, Ajioka J W
Department of Pathology, University of Cambridge, UK.
Mol Biochem Parasitol. 1997 Feb;84(2):203-14. doi: 10.1016/s0166-6851(96)02796-x.
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.
弓形虫的表达序列标签（EST）数据集为基因发现提供了丰富的信息。EST tgc050位点的完整cDNA和基因组序列表明，它包含五个保守的血小板反应蛋白（TSP）样基序拷贝，这些基序存在于许多具有粘附特性的分子中。该分子中还存在一个与包括几种整合素在内的另一组蛋白质的粘附特性相关的保守区域。该序列编码的蛋白（rc50）被抗MIC2单克隆抗体强烈识别。亲和纯化的抗rc50抗血清与一种分子量与MIC2相同的单一蛋白特异性反应，并通过冷冻免疫电子显微镜专门标记了弓形虫的微线体。这些结果表明，c50编码MIC2，一种先前已鉴定的弓形虫微线体蛋白。多个蛋白质结构域的广泛序列相似性提供了证据，表明该位点编码的蛋白是柔嫩艾美耳球虫Etp100微线体蛋白的同源物。
