Lee-Huang S, Lee H, Ochoa S
Proc Natl Acad Sci U S A. 1974 Aug;71(8):2928-31. doi: 10.1073/pnas.71.8.2928.
We have previously reported the isolation from E. coli of a specific inhibitor of polypeptide chain initiation that is rendered ineffective when active aminoacylation of transfer RNA is taking place; this is normally the case during natural messenger RNA translation. Surprisingly, the inhibitory activity appears to be a hitherto unrecognized property of the chain elongation factor G. The following hold for preparations purified for either translocase or inhibitor activity: (1) equal electrophoretic mobility on polyacrylamide gels; (2) equal specific activities for (a) inhibition of initiation, (b) translocation, and (c) ribosome-dependent, uncoupled GTPase; and (3) similar heat sensitivity of translocase and inhibitor activities in a temperature-sensitive E. coli mutant with an altered elongation factor G. Different sites are apparently involved in translocation and inhibition because the former, but not the latter, is sensitive to p-chloromercuribenzoate and fusidic acid.
我们之前报道过从大肠杆菌中分离出一种多肽链起始的特异性抑制剂，当转运RNA进行活性氨酰化时，该抑制剂会失效；在天然信使RNA翻译过程中通常就是这种情况。令人惊讶的是，这种抑制活性似乎是迄今未被认识到的延伸因子G的一种特性。对于为转位酶或抑制剂活性而纯化的制剂，以下情况成立：（1）在聚丙烯酰胺凝胶上具有相同的电泳迁移率；（2）对于（a）起始抑制、（b）转位和（c）核糖体依赖性、非偶联GTP酶具有相同的比活性；（3）在具有改变的延伸因子G的温度敏感型大肠杆菌突变体中，转位酶和抑制剂活性具有相似的热敏感性。转位和抑制显然涉及不同的位点，因为前者（而非后者）对对氯汞苯甲酸和夫西地酸敏感。
