Borst P, Fairlamb A H
The Netherlands Cancer Institute, Division of Molecular Biology, Amsterdam, The Netherlands.
Annu Rev Microbiol. 1998;52:745-78. doi: 10.1146/annurev.micro.52.1.745.
African trypanosomes combine antigenic variation of their surface coat with the ability to take up nutrients from their mammalian hosts. Uptake of small molecules such as glucose or nucleosides is mediated by translocators hidden from host antibodies by the surface coat. The multiple glucose transporters and transporters for nucleobases and nucleosides have been characterized. Receptors for host macromolecules such as transferrin and lipoproteins are visible to antibodies but hidden from the cellular arm of the host immune system in an invagination of the trypanosome surface, the flagellar pocket. The trypanosomal transferrin receptor is a heterodimer that resembles the major component of the surface coat of Trypanosoma brucei. The ability to make several versions of this receptor allows T. brucei to bind transferrins from a range of mammals with high affinity. The proteins required for uptake of nutrients by trypanosomes provide a target for chemotherapy that remains to be fully exploited.
非洲锥虫将其表面被膜的抗原变异与从哺乳动物宿主摄取营养的能力结合起来。诸如葡萄糖或核苷等小分子的摄取是由被表面被膜隐藏起来、宿主抗体无法识别的转运蛋白介导的。多种葡萄糖转运蛋白以及核碱基和核苷转运蛋白已得到表征。诸如转铁蛋白和脂蛋白等宿主大分子的受体可被抗体识别，但在锥虫表面的内陷结构——鞭毛袋中，却能躲避宿主免疫系统的细胞免疫。锥虫转铁蛋白受体是一种异二聚体，类似于布氏锥虫表面被膜的主要成分。能够产生该受体的多种变体，使布氏锥虫能够以高亲和力结合多种哺乳动物的转铁蛋白。锥虫摄取营养所需的蛋白质为化疗提供了一个尚未得到充分利用的靶点。
