Havercroft J C, Huggins M C, Dunne D W, Taylor D W
Department of Pathology, University of Cambridge, U.K.
Mol Biochem Parasitol. 1990 Jan 15;38(2):211-9. doi: 10.1016/0166-6851(90)90024-g.
A cDNA clone encoding part of a 20-kDa antigen of Schistosoma mansoni (Sm20) has been isolated. The amino acid sequence of this antigen, as predicted from the sequence of the cDNA, has significant homology to the family of calcium binding proteins which include calmodulin, troponin C and the light chain of myosin. Although we have been unable to show any immunological cross-reactivity between Sm20 and calmodulins from a range of other species, we have verified that Sm20 is a functional calcium binding protein. Sm20 is encoded by a small multigene family and is expressed in schistosomula and adult worms but not in eggs. The 20-kDa nascent polypeptide appears to be post-translationally modified to give a 38-kDa species. Sm20 is present in preparations of tegumental membranes and is easily removed from intact schistosomula by detergent treatment, suggesting that it is associated with the tegument. However, the cloned portion does not appear to be exposed on the surface.
已分离出一个编码曼氏血吸虫20 kDa抗原（Sm20）部分序列的cDNA克隆。根据cDNA序列预测，该抗原的氨基酸序列与包括钙调蛋白、肌钙蛋白C和肌球蛋白轻链在内的钙结合蛋白家族具有显著同源性。尽管我们未能显示Sm20与一系列其他物种的钙调蛋白之间存在任何免疫交叉反应，但我们已证实Sm20是一种功能性钙结合蛋白。Sm20由一个小的多基因家族编码，在童虫和成虫中表达，但在虫卵中不表达。20 kDa的新生多肽似乎经过翻译后修饰形成了38 kDa的产物。Sm20存在于体表膜制剂中，通过去污剂处理可轻易从完整的童虫中去除，这表明它与体表相关。然而，克隆的部分似乎并未暴露在表面。
