弓形虫是专性细胞内寄生虫，囊泡成管和缢缩是虫体囊泡形成与转运的起始和关键阶段，对弓形虫的生存和致病性至关重要，其关键蛋白和作用机理一直未有解析。哺乳动物细胞中，BAR（Bin-Amphiphysin-Rvs）蛋白在囊泡出芽的成管和缢缩阶段发挥重要作用。前期我们发现了一个包含BAR结构域的弓形虫蛋白，命名为BAR-domain Containing Protein 1（BCP1）；BCP1是弓形虫生长的关键蛋白，定位于高尔基体和内体区域，与内溶酶体部分共定位；推测BCP1参与了虫体囊泡的形成及转运。本项目拟通过1）明确BCP1的亚细胞定位、2）检测BCP1对弓形虫表型的影响、3）解析BCP1互作蛋白并鉴定关键蛋白功能、4）电镜检测验证BCP1的促膜成管活性等，探索BCP1蛋白在虫体囊泡出芽及转运中的功能和作用机理。预期结果将为阐明弓形虫BAR蛋白的生物学功能及寻找抗弓形虫药物新靶点提供依据。

Toxoplasma gondii is an obligate intracellular parasite. Vesicle tubulation and constriction are the initial and critical stages of vesicle formation and transport, which are crucial to the survival and pathogenicity of toxoplasma. The key proteins and the mechanism involved have not been elucidated. BAR (Bin-Amphiphysin-Rvs) proteins are involved in the tubulation and constriction of budding vesicles in mammalian cells. Our previous bioinformatics analysis revealed a toxoplasma protein containing the structural domain of BAR, named Bar-domain Containing Protein 1 (BCP1). We have also found that BCP1 is essential for parasite growth and located at the Golgi and endosomal region. BCP1 has also been detected to partially co-localize with VAC, suggesting that BCP1 is involved in the vesicle transport pathway of nutrient exchange. Therefore, the applicant proposes, (1) to identify the subcellular localization of BCP1; (2) to detect the phenotypes such as toxoplasma invasion, proliferation and escape; (3) to analyze the BCP1-mediated protein interaction and identify the key proteins; (4) to verify the activity of BCP1 in promoting vesicle tubulation and constriction by EM, and other experiments. We aim to explore the roles of BCP1 in vesicle formation and transport. It is expected that the findings of this proposed project will elucidate the basic biological functions of BCP1, and provide the theoretical foundation of new anti-toxoplasma drug targets.