Zarucki-Schulz T, Jerez C, Goldberg G, Kung H F, Huang K H, Brot N, Weissbach H
Proc Natl Acad Sci U S A. 1979 Dec;76(12):6115-9. doi: 10.1073/pnas.76.12.6115.
The in vitro synthesis of elongation factor (EF)-Tu (tufB), the beta beta' subunits of RNA polymerase, ribosomal proteins L10 and L12 directed by DNA from the transducing phage lambda rifd 18, EF-Tu (tufA), EF-G, and the alpha subunit of RNA polymerase directed by DNA from the transducing phage lambda fus3 has been investigated in a crude and a partially defined protein-synthesizing system. Proteins L10 and L12 are synthesized in the partially defined system almost as well as in the crude system. However, the synthesis of EF-Tu, EF-G, and the alpha and beta beta' subunits of RNA polymerase is far less efficient in the partially defined system. An active fraction that stimulates the synthesis of these latter proteins has been obtained by fractionation of a high-speed supernatant on DEAE-cellulose. Because previous studies showed that this fraction (1 M DEAE salt eluate) contains a protein, called L factor, that stimulates beta-galactosidase synthesis in vitro, L factor was tested for activity. Although L factor stimulates the synthesis of the beta beta' subunits, it has little or no effect on the in vitro synthesis of the other products studied. In the present experiments, the ratio of L12/L10 and of EF-Tu (tufA)/EF-G formed is 4-6. These values are consistent with in vivo results.
在粗制和部分限定的蛋白质合成系统中，研究了由转导噬菌体λrifd 18的DNA指导的延伸因子（EF）-Tu（tufB）、RNA聚合酶的ββ'亚基、核糖体蛋白L10和L12的体外合成，以及由转导噬菌体λfus3的DNA指导的EF-Tu（tufA）、EF-G和RNA聚合酶的α亚基的体外合成。在部分限定的系统中，蛋白质L10和L12的合成效率几乎与在粗制系统中一样。然而，在部分限定的系统中，EF-Tu、EF-G以及RNA聚合酶的α和ββ'亚基的合成效率要低得多。通过在DEAE-纤维素上对高速上清液进行分级分离，获得了一种刺激后一种蛋白质合成的活性组分。因为先前的研究表明，该组分（1 M DEAE盐洗脱液）含有一种称为L因子的蛋白质，它在体外刺激β-半乳糖苷酶的合成，所以对L因子的活性进行了测试。虽然L因子刺激ββ'亚基的合成，但对所研究的其他产物的体外合成几乎没有影响。在本实验中，形成的L12/L10和EF-Tu（tufA）/EF-G的比例为4-6。这些值与体内结果一致。
