STRUCTURAL STUDIES OF THE SCRAPIE PRION PROTEIN USING MASS-SPECTROMETRY AND AMINO-ACID SEQUENCING
STRUCTURAL STUDIES OF THE SCRAPIE PRION PROTEIN USING MASS-SPECTROMETRY AND AMINO-ACID SEQUENCING
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DOI：
10.1021/bi00059a016
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发表时间：
1993-03-02
期刊：
影响因子：
2.9
通讯作者：
PRUSINER, SB
中科院分区：
文献类型：
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作者：
STAHL, N;BALDWIN, MA;PRUSINER, SB
到目前为止，传染性羊瘙痒症朊病毒的唯一成分是一种名为PrP（Sc）的蛋白质。 翻译后过程将细胞PrP同种型（PrP（C））转化为PrP（Sc）。用内切蛋白酶消化变性的PrP（Sc），并通过HPLC分离所得片段。通过质谱和Edman测序，发现PrP（Sc）的一级结构与PrP基因序列推测的一级结构相同，认为PrP（Sc）的合成既不涉及RNA编辑，也不涉及蛋白质剪接。质谱法还用于搜索除了连接到C-末端的糖基肌醇磷脂锚和已知在PrP（Sc）和PrP（C）上发生的两个Asn连接的寡糖之外的翻译后化学修饰。这些结果表明，PrP（Sc）分子在氨基酸取代或翻译后化学修饰的水平上与PrP（C）没有区别;然而，我们不能排除一小部分PrP（Sc）被尚未确定的翻译后过程修饰或PrP（C）携带在PrP（Sc）形成过程中被去除的修饰的可能性。PrP（Sc）似乎在二级和三级结构上与PrP（C）不同，但也必须考虑与PrP（Sc）纯化的紧密结合的疾病特异性分子的可能性。
The only component of the infectious scrapie prion identified to date is a protein designated PrP(Sc). A posttranslational process converts the cellular PrP isoform (PrP(C)) into PrP(Sc). Denatured PrP(Sc) was digested with endoproteases, and the resulting fragments were isolated by HPLC. By both mass spectrometry and Edman sequencing, the primary structure of PrP(Sc) was found to be the same as that deduced from the PrP gene sequence, arguing that neither RNA editing nor protein splicing feature in the synthesis of PrP(Sc). Mass spectrometry also was used to search for posttranslational chemical modifications other than the glycosylinositol phospholipid anchor attached to the C-terminus and two Asn-linked oligosaccharides already known to occur on both PrP(Sc) and PrP(C). These results contend that PrP(Sc) molecules do not differ from PrP(C) at the level of an amino acid substitution or a posttranslational chemical modification; however, we cannot eliminate the possibility that a small fraction of PrP(Sc) is modified by an as yet unidentified posttranslational process or that PrP(C) carries a modification that is removed in the formation of PrP(Sc). It seems likely that PrP(Sc) differs from PrP(C) in its secondary and tertiary structure, but the possibility of a tightly bound, disease-specific molecule which purifies with PrP(Sc) must also be considered.