Pays E
Département de Biologie Moléculaire, Université Libre de Bruxelles, Belgique.
Ann Parasitol Hum Comp. 1990;65 Suppl 1:5-10. doi: 10.1051/parasite/1990651005.
Although several hundred of different antigen genes exist in the trypanosome genome, only one is usually expressed at a time. This expression occurs in one of several possible telomeric expression sites. Besides being exclusively telomeric, transcription of the antigen gene exhibits other particular characteristics: the RNA polymerase is highly resistant to alpha-amanitin, and the transcription unit comprises several other genes, one of which may encode an adenylate cyclase. Post-transcriptional controls modulate the activity of this transcription unit during the parasite life-cycle. Antigenic variation is achieved through either alternative activation of different expression sites, or gene recombination within a given expression site. These mechanisms ensure a relative programming of antigen expression.
尽管锥虫基因组中存在数百种不同的抗原基因，但通常一次只表达一种。这种表达发生在几个可能的端粒表达位点之一。除了完全位于端粒外，抗原基因的转录还表现出其他特殊特征：RNA聚合酶对α-鹅膏蕈碱高度耐药，转录单元还包含其他几个基因，其中一个可能编码腺苷酸环化酶。转录后调控在寄生虫生命周期中调节该转录单元的活性。抗原变异通过不同表达位点的交替激活或给定表达位点内的基因重组来实现。这些机制确保了抗原表达的相对程序性。
