Department of Pathology, Case Western Reserve University, Cleveland, Ohio 44106, USA.
J Biol Chem. 2010 Oct 1;285(40):30489-95. doi: 10.1074/jbc.M110.161794. Epub 2010 Jul 29.
The presence of the prion protein (PrP) in normal human urine is controversial and currently inconclusive. This issue has taken a special relevance because prion infectivity has been demonstrated in urine of animals carrying experimental or naturally occurring prion diseases, but the actual presence and tissue origin of the infectious prion have not been determined. We used immunoprecipitation, one- and two-dimensional electrophoresis, and mass spectrometry to prove definitely the presence of PrP in human urine and its post-translational modifications. We show that urinary PrP (uPrP) is truncated mainly at residue 112 but also at other residues up to 122. This truncation makes uPrP undetectable with some commonly used antibodies to PrP. uPrP is glycosylated and carries an anchor which, at variance with that of cellular PrP, lacks the inositol-associated phospholipid moiety, indicating that uPrP is probably shed from the cell surface. The detailed characterization of uPrP reported here definitely proves the presence of PrP in human urine and will help determine the origin of prion infectivity in urine.
朊病毒蛋白（PrP）在正常人体尿液中的存在一直存在争议，目前尚无定论。这个问题变得尤为重要，因为已经在患有实验性或天然朊病毒病的动物的尿液中证明了朊病毒的感染性，但尚未确定传染性朊病毒的实际存在和组织来源。我们使用免疫沉淀、一维和二维电泳以及质谱技术，明确证明了 PrP 确实存在于人体尿液中，并对其进行了翻译后修饰。我们发现尿中的 PrP（uPrP）主要在残基 112 处截断，但也在其他残基处截断，截断长度可达 122 个残基。这种截断使得一些常用的 PrP 抗体无法检测到 uPrP。uPrP 糖基化，并带有一个锚定，与细胞 PrP 的锚定不同，它缺乏与肌醇相关的磷脂部分，表明 uPrP 可能是从细胞表面脱落的。本研究中对 uPrP 的详细特征分析明确证明了 PrP 确实存在于人体尿液中，并将有助于确定尿液中朊病毒感染性的来源。
