Werner E B, Taylor W R, Holder A A
Division of Parasitology, National Institute for Medical Research, London, UK.
Mol Biochem Parasitol. 1998 Aug 1;94(2):185-96. doi: 10.1016/s0166-6851(98)00067-x.
cDNA and genomic DNA clones covering the entire open reading frame (ORF) for a Plasmodium chabaudi 96V protein were isolated. From the first ATG codon the intronless gene codes for a 229-kDa protein. Antisera raised against recombinant polypeptides coded by two different regions of the gene reacted with a 240/225-kDa doublet on Western blots of parasite extracts. In immunofluorescence studies the same sera detected the antigen at the apical end of the merozoite, possibly in rhoptry organelles. In Western blotting experiments the recombinant polypeptides were recognised by antibodies induced by natural infection. A 364-amino acid residue repetitive region, based on 32 11-mer repeats divided by two 6-mer repeats into three blocks, is located in the centre of the protein. Analysis of this repetitive region led us to propose a model in which each of the three units forms an alpha-helical coiled-coil triple-helix containing a possible leucine-histidine zipper. Each unit resembles in structure the units present in spectrin. The repeat region is flanked by predicted heptad based alpha-helical coiled-coil regions, and we propose that the protein forms a dimer. The 229-kDa protein has the overall character of a cytoskeletal protein. We have named the 229-kDa protein repetitive organellar protein (ROPE) and suggest that ROPE may be involved in the process of invasion, possibly by interacting with the erythrocyte cytoskeleton, and that the leucine histidine-zipper may be involved in molecular mimicry of spectrin.
分离出了覆盖查巴迪疟原虫96V蛋白整个开放阅读框（ORF）的cDNA和基因组DNA克隆。从第一个ATG密码子开始，这个无内含子基因编码一种229 kDa的蛋白质。针对该基因两个不同区域编码的重组多肽产生的抗血清，在寄生虫提取物的蛋白质印迹上与一个240/225 kDa的双峰发生反应。在免疫荧光研究中，相同的血清在裂殖子的顶端检测到该抗原，可能存在于棒状体细胞器中。在蛋白质印迹实验中，重组多肽被自然感染诱导产生的抗体识别。一个由32个11聚体重复序列组成、被两个6聚体重复序列分成三个结构域的364个氨基酸残基的重复区域，位于该蛋白质的中心。对这个重复区域的分析使我们提出一个模型，其中三个单元中的每一个都形成一个α螺旋卷曲螺旋三螺旋结构，包含一个可能的亮氨酸-组氨酸拉链。每个单元在结构上类似于血影蛋白中的单元。重复区域两侧是基于七肽的预测α螺旋卷曲螺旋区域，我们提出该蛋白质形成二聚体。229 kDa的蛋白质具有细胞骨架蛋白的总体特征。我们将229 kDa的蛋白质命名为重复细胞器蛋白（ROPE），并认为ROPE可能参与入侵过程，可能是通过与红细胞细胞骨架相互作用，并且亮氨酸-组氨酸拉链可能参与血影蛋白的分子模拟。
