Paushkin S V, Kushnirov V V, Smirnov V N, Ter-Avanesyan M D
Institute of Experimental Cardiology, Cardiology Research Center, 3rd Cherepkovskaya Street 15A, Moscow 121552, Russia.
Science. 1997 Jul 18;277(5324):381-3. doi: 10.1126/science.277.5324.381.
The yeast cytoplasmically inherited genetic determinant [PSI+] is presumed to be a manifestation of the prion-like properties of the Sup35 protein (Sup35p). Here, cell-free conversion of Sup35p from [psi-] cells (Sup35ppsi-) to the prion-like [PSI+]-specific form (Sup35pPSI+) was observed. The conversion reaction could be repeated for several consecutive cycles, thus modeling in vitro continuous [PSI+] propagation. Size fractionation of lysates of [PSI+] cells demonstrated that the converting activity was associated solely with Sup35pPSI+ aggregates, which agrees with the nucleation model for [PSI+] propagation. Sup35pPSI+ was purified and showed high conversion activity, thus confirming the prion hypothesis for Sup35p.
酵母细胞质遗传决定因子[PSI+]被推测是Sup35蛋白（Sup35p）的类朊病毒特性的一种表现形式。在此，观察到来自[psi-]细胞（Sup35ppsi-）的Sup35p在无细胞体系中转化为类朊病毒的[PSI+]特异性形式（Sup35pPSI+）。该转化反应可以连续重复几个循环，从而在体外模拟[PSI+]的持续传播。对[PSI+]细胞裂解物进行大小分级分离表明，转化活性仅与Sup35pPSI+聚集体相关，这与[PSI+]传播的成核模型相符。Sup35pPSI+被纯化并显示出高转化活性，从而证实了Sup35p的朊病毒假说。
