Chang C N, Blobel G, Model P
Proc Natl Acad Sci U S A. 1978 Jan;75(1):361-5. doi: 10.1073/pnas.75.1.361.
An inverted membrane vesicle fraction isolated from uninfected Escherichia coli and largely derived from the inner membrane has been shown to contain an endoproteolytic activity that cleaves nascent bacteriophage f1 pre-coat protein into two identifiable products. The electrophoretic mobility on sodium dodecyl sulfate/urea/polyacrylamide gels and the partial amino-terminal sequence of the larger fragment were indistinguishable from those of the mature phage coat protein. Partial amino-terminal sequence analysis showed that the smaller fragment corresponds to the amino-terminal "signal peptide" of f1 pre-coat protein. Cleavage occurred only if the membrane fraction was present during in vitro synthesis, and was not observed if it was added after completion of pre-coat protein synthesis. The cleavage reaction was strongly stimulated when the membrane fraction was present together with the nonionic detergent Nikkol. These results are consistent with and discussed in terms of the signal hyothesis.
从未感染的大肠杆菌中分离出的一种倒置膜泡组分，其主要来源于内膜，已被证明含有一种内切蛋白水解活性，该活性可将新生的噬菌体f1前衣壳蛋白切割成两种可识别的产物。在十二烷基硫酸钠/尿素/聚丙烯酰胺凝胶上的电泳迁移率以及较大片段的部分氨基末端序列与成熟噬菌体衣壳蛋白的电泳迁移率和部分氨基末端序列无法区分。部分氨基末端序列分析表明，较小的片段对应于f1前衣壳蛋白的氨基末端“信号肽”。切割仅在体外合成过程中存在膜组分时发生，如果在衣壳蛋白合成完成后添加膜组分则未观察到切割现象。当膜组分与非离子去污剂Nikkol一起存在时，切割反应受到强烈刺激。这些结果与信号假说一致并据此进行了讨论。
