“疯牛病”与“疯人病”——蛋白粒与蛋白粒疾病

蛋白粒是一个不含核苷酸的蛋白性粒子，能够传染动物和人．引起大脑损伤及死亡．蛋白粒疾病包括羊瘙痒病、牛海绵体脑炎、人的克氏-约氏病、杰氏-斯氏-斯氏病以及致命性家族失眠症．本文从蛋白粒与人类和动物疾病的关系，回顾了蛋白粒疾病发生及传染的过程．具有不同氨基酸组成的蛋白粒，存在着可溶性的ＰｒＰC型及不溶性ＰｒＰＳＣ型．只有ＰｒＰＳＣ是传染性的．通过对蛋白粒结构与功能的剖析，讨论了蛋白粒的基因、蛋白粒的产生以及可能的致病机理（Ｘ蛋白被发现与细胞内蛋白粒增生有关）．最后，对蛋白质、ＤＮＡ和ＲＮＡ之间的遗传信息流提出了一个新的假说．

Mad Cow Disease

Prion is a protein particle containing no nucleic acids, capable of transmitting diseases that cause brain damage and death. Prion diseases include scrapie, bovine spongiform encephalopathy, Creutzfeldt-Jakob disease, Gerstmann-Straussler-Scheinker disease, and fatal familial insomnia. This article reviews the discovery and transmission of prions based on the relationship between prions and the diseases of human beings and animals. Prions with different amino acid composition exist as the PrP^SC insoluble form and the PrP^Csoluble form. Only PrP^SCis infectious. Based on the structure and function of the prion protein and the prion genes, a possible mechanism of prion infection has been discussed. Protein X is found involved in the prion propagation. A hypothesis of the relationship among protein, DNA and RNA is proposed.