STRUCTURE OF THE VARIANT GLYCOPROTEINS AND SURFACE-COAT OF TRYPANOSOMA-BRUCEI
STRUCTURE OF THE VARIANT GLYCOPROTEINS AND SURFACE-COAT OF TRYPANOSOMA-BRUCEI
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DOI：
10.1098/rstb.1984.0104
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发表时间：
1984-01-01
影响因子：
6.3
通讯作者：
CROSS, GAM
中科院分区：
文献类型：
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作者：
CROSS, GAM
致病性非洲锥虫具有独特的抗原变异机制。每个细胞表面覆盖一层由。apprx组成的涂层。从大量变体中提取的700万个基本相同的糖蛋白分子，每个变体都由一个单独的基因编码。氨基酸序列的变化延伸到整个分子，但从氨基端减少到羧基端，其中某些特征，特别是半胱氨酸残基的分组，是相当保守的。在每个细胞中存在的大约一千种不同的糖蛋白基因的多样性范围是很大的。新的变异可以通过片段基因转换瞬间产生。由氨基末端信号序列和疏水羧基末端尾部合成了变异表面糖蛋白。尾巴非常保守。合成后，它们被一种复杂的糖脂结构所取代，在这种糖脂结构中，肉豆蔻酸（十二烷酸）将多肽固定在表面膜上。肉豆蔻酸的酶裂解从表面释放出不同的糖蛋白。
The pathogenic African trypanosomes have a unique mechanism for antigenic variation. Each cell is overed by a surface coat consisting of .apprx. 7 million essentially identical glycoprotein molecules drawn from a large repertoire of variants, each encoded by an individual gene. Amino acid sequence variation extends throughout the molecule but reduces from the amino terminus to the carboxy terminus, where certain features, especially the grouping of cysteine residues, are quite conserved. The range of diversity within the thousand or so variant glycoprotein genes that exist in each cell is large. New variants may arise instantaneously by segmental gene conversion. Variant surface glycoproteins are synthesized with amino terminal signal sequences and hydrophobic carboxy terminal tails. The tails are extraordinarily conserved. After synthesis, they are replaced by a complex glycolipid structure in which myristic (dodecanoic) acid serves to anchor the polypeptide to the surface membrane. Enzymic cleavage of myristic acid releases variant glycoproteins from the surface coat.