Etzion Z, Murray M C, Perkins M E
Laboratory of Biochemical Parasitology, Rockefeller University, New York, NY 10021.
Mol Biochem Parasitol. 1991 Jul;47(1):51-61. doi: 10.1016/0166-6851(91)90147-x.
Rhoptries have been isolated from Plasmodium falciparum schizont-infected erythrocytes by isopycnic density centrifugation. Gradient fractions were analyzed by immunoblotting with antibodies against two polypeptides of 140 and 110 kDa, known to be components of the rhoptry. The proteins were present primarily in fractions with a density of 1.16 g ml-1. Electron microscopy of these fractions indicated they were enriched in rhoptries. For the most part, the isolated organelle retained in situ morphology, although some rhoptries were distorted, indicating the structure of some of the organelles is not rigid. Electrophoretic analysis of the rhoptry fractions indicated the presence of a number of proteins, many of which have not been identified to date. Properties of proteins in the isolated rhoptry were examined using the 140 and 110 kDa proteins as representative markers. Both proteins are present in a complex with a 130-kDa protein, as all three co-immunoprecipitate. At the late schizont stage, the rhoptry proteins are present in two distinct forms; a soluble form with an Mr of 480 000 which would correspond to a single copy of the 140/130/110 kDa complex and a form that can be sedimented at 130 000 x g. Properties of the sedimentable form suggest that the proteins are included in structures that resemble membranes. Ionic detergents were required to solubilize the proteins while high concentrations of NaCl and Na2CO3 resulted in only partial solubilization. Furthermore, treatment of disrupted rhoptries with phospholipase A and C resulted in the release of proteins into the soluble form.
通过等密度离心法已从恶性疟原虫裂殖体感染的红细胞中分离出棒状体。用针对已知为棒状体成分的两种140 kDa和110 kDa多肽的抗体，通过免疫印迹分析梯度级分。这些蛋白质主要存在于密度为1.16 g/ml的级分中。对这些级分进行电子显微镜检查表明，它们富含棒状体。在大多数情况下，分离出的细胞器保留了原位形态，尽管有些棒状体发生了变形，这表明一些细胞器的结构并不坚硬。对棒状体级分的电泳分析表明存在许多蛋白质，其中许多迄今尚未鉴定。以140 kDa和110 kDa蛋白质作为代表性标记物，研究了分离出的棒状体中蛋白质的特性。这两种蛋白质都与一种130 kDa的蛋白质形成复合物，因为这三种蛋白质都能共同免疫沉淀。在裂殖体后期，棒状体蛋白质以两种不同的形式存在；一种可溶性形式，Mr为480 000，相当于140/130/110 kDa复合物的单拷贝，另一种形式可以在130 000×g下沉淀。可沉淀形式的特性表明这些蛋白质包含在类似膜的结构中。需要离子去污剂来溶解这些蛋白质，而高浓度的NaCl和Na2CO3只能导致部分溶解。此外，用磷脂酶A和C处理破碎的棒状体导致蛋白质释放到可溶性形式中。
