Legon S, Model P, Robertson H D
Proc Natl Acad Sci U S A. 1977 Jul;74(7):2692-6. doi: 10.1073/pnas.74.7.2692.
We have compared the behavior of a prokaryotic mRNA in a eukaryotic ribosome binding system and of a eukaryotic mRNA in a prokaryotic ribosome binding system. Using (32)P- and (125)I-labeled bacteriophage f1 mRNA, we have shown that rabbit reticulocyte 80S ribosomes can protect specific sequences from pancreatic RNase digestion, including those sequences protected by Escherichia coli ribosomes. We have also found that E. coli ribosomes fail to protect any region of (125)I-labeled globin mRNA. Iodination of the mRNA appeared to have little or no effect on the specificity of binding or protection by the ribosomes of either system.The eukaryotic and prokaryotic systems differ markedly in the ability of the small ribosomal subunits to protect mRNA from nuclease digestion. The regions of phage f1 mRNA protected by E. coli 30S subunits are virtually identical to those protected by the 70S ribosomes. By contrast, rabbit reticulocyte 40S subunits protect substantially larger fragments of mRNA from nuclease digestion than do the 80S ribosomes. These 40S-protected fragments are specific in the case of globin mRNA and overlap the shorter region protected by the 80S ribosomes. However, the 40S-protected fragments of phage f1 mRNA were found to be extremely heterogeneous, reflecting perhaps an important difference between the initial interactions made by these two mRNAs with the ribosomes.
我们比较了原核生物mRNA在真核核糖体结合系统中的行为以及真核生物mRNA在原核核糖体结合系统中的行为。使用（32）P和（125）I标记的噬菌体f1 mRNA，我们发现兔网织红细胞80S核糖体可以保护特定序列免受胰腺核糖核酸酶消化，包括那些被大肠杆菌核糖体保护的序列。我们还发现大肠杆菌核糖体无法保护（125）I标记的珠蛋白mRNA的任何区域。mRNA的碘化似乎对两个系统中核糖体的结合或保护特异性几乎没有影响。真核和原核系统在小核糖体亚基保护mRNA免受核酸酶消化的能力上有显著差异。被大肠杆菌30S亚基保护的噬菌体f1 mRNA区域与被70S核糖体保护的区域几乎相同。相比之下，兔网织红细胞40S亚基比80S核糖体保护的mRNA片段大得多，免受核酸酶消化。在珠蛋白mRNA的情况下，这些40S保护的片段是特异性的，并且与80S核糖体保护的较短区域重叠。然而，发现噬菌体f1 mRNA的40S保护片段极其不均一，这可能反映了这两种mRNA与核糖体最初相互作用之间的重要差异。
