CONVERSION OF TRUNCATED AND ELONGATED PRION PROTEINS INTO THE SCRAPIE ISOFORM IN CULTURED-CELLS
CONVERSION OF TRUNCATED AND ELONGATED PRION PROTEINS INTO THE SCRAPIE ISOFORM IN CULTURED-CELLS
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DOI：
10.1073/pnas.90.8.3182
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发表时间：
1993-04-15
影响因子：
11.1
通讯作者：
PRUSINER, SB
中科院分区：
文献类型：
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作者：
ROGERS, M;YEHIELY, F;PRUSINER, SB
感染性朊病毒的唯一已知成分是一种经过后修饰的蛋白质，称为朊病毒蛋白的羊瘙痒病同种型，PrP（Sc）。在有限的蛋白水解后，形成了一个称为PrP 27-30的蛋白酶抗性片段。使用体外诱变，我们研究的N和C末端的持续感染，小鼠神经母细胞瘤（ScN 2a）细胞中形成的PrP（Sc）的作用。氨基酸23-88的缺失（在PrP 27-31的形成中也被蛋白酶K去除）和该区域内五个八肽重复的缺失都不会改变PrP（Sc）的合成。除了在野生型PrP中发现的五个八肽重复外，PrP与一个、两个、四个或六个八肽重复的延长并没有改变PrP（Sc）的合成。通过用翻译终止密码子取代预测的对应于氨基酸231-254的糖基肌醇磷脂（GPI）锚定附着信号来实现C末端的截短。这种C-末端PrP突变体在ScN 2a细胞中的表达产生了似乎缺乏GPI锚的PrP（Sc）。我们的结论是，无论是GPI锚，也不是N-末端66个氨基酸的合成所需的PrP（Sc）的测定收购有限的抵抗蛋白酶K消化。这些截短或延长的PrP分子是否能够参与感染性朊病毒的形成仍有待确定。
The only known component of the infectious prion is a posttranslationally modified protein known as the scrapie isoform of the prion protein, PrP(Sc). Upon limited proteolysis, a protease-resistant fragment designated PrP 27-30 is formed. Using in vitro mutagenesis, we examined the role of the N and C termini in the formation of PrP(Sc) in persistently infected, mouse neuroblastoma (ScN2a) cells. Neither deletion of amino acids 23-88, which are also removed by proteinase K in the formation of PrP 27-31), nor deletion of the five octapeptide repeats within this region altered synthesis of PrP(Sc). Elongation of PrP with one, two, four, or six octapeptide repeats in addition to the five found in wild-type PrP did not alter the synthesis of PrP(Sc). Truncation of the C terminus was accomplished by substituting a translation stop codon for the predicted glycosylinositol phospholipid (GPI) anchor-attachment signal corresponding to amino acids 231-254. Expression of this C-terminal PrP mutant in ScN2a cells produced PrP(Sc) that appeared to lack a GPI anchor. We conclude that neither the GPI anchor nor the N-terminal 66 amino acids are required for the synthesis of PrP(Sc) as measured by the acquisition of limited resistance to proteinase K digestion. Whether these truncated or elongated PrP molecules are competent to participate in the formation of infectious prions remains to be established.