During its intraerythrocytic life cycle, the human malaria parasite Plasmodium falciparum supplements its nutritional requirements by scavenging substrates from the plasma through the new permeability pathways (NPPs) installed in the red blood cell (RBC) membrane. Parasite proteins of the RhopH complex: CLAG3, RhopH2, RhopH3, have been implicated in NPP activity. Here, we studied 13 exported proteins previously hypothesised to interact with RhopH2, to study their potential contribution to the function of NPPs. NPP activity assays revealed that the 13 proteins do not appear to be individually important for NPP function, as conditional knockdown of these proteins had no effect on sorbitol uptake. Intriguingly, reciprocal immunoprecipitation assays showed that five of the 13 proteins interact with all members of the RhopH complex, with PF3D7_1401200 showing the strongest association. Mass spectrometry-based proteomics further identified new protein complexes; a cytoskeletal complex and a Maurer's clefts/J-dot complex, which overall helps clarify protein–protein interactions within the infected RBC (iRBC) and is suggestive of the potential trafficking route of the RhopH complex itself to the RBC membrane.

中文翻译：

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由输出到恶性疟原虫感染的红细胞宿主细胞室的寄生虫蛋白形成的复合物的表征

在其红细胞内生命周期中，人类疟疾寄生虫恶性疟原虫通过安装在红细胞 (RBC) 膜中的新渗透通路 (NPP) 从血浆中清除底物，补充其营养需求。RhopH 复合物的寄生虫蛋白：CLAG3、RhopH2、RhopH3，与 NPP 活性有关。在这里，我们研究了以前假设与 RhopH2 相互作用的 13 种输出蛋白质，以研究它们对 NPP 功能的潜在贡献。NPP 活性测定表明，这 13 种蛋白质似乎对 NPP 功能并不重要，因为这些蛋白质的条件性敲低对山梨糖醇的摄取没有影响。有趣的是，相互免疫沉淀测定表明，13 种蛋白质中的 5 种与 RhopH 复合体的所有成员相互作用，其中 PF3D7_1401200 显示出最强的关联。基于质谱的蛋白质组学进一步鉴定了新的蛋白质复合物；一个细胞骨架复合物和一个毛勒裂/J-点复合物，总体上有助于阐明受感染红细胞 (iRBC) 内的蛋白质-蛋白质相互作用，并暗示 RhopH 复合物本身到红细胞膜的潜在运输途径。