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tRNA-Ribosome Interactions

Charles R. Cantor


The bacterial ribosome is 100 times the molecular weight of tRNA. Ribosomes from eukaryotes are even larger. Thus, a detailed description of ribosome structure and the mechanism of protein synthesis could dwarf a book about tRNA (for recent reviews, see Nomura et al. 1974; Weissbach and Pestka 1977; Kurland 1977; Brimacombe et al. 1978; Grunberg-Manago et al. 1978). Here we shall focus on ribosome-tRNA interactions from the myopic point of view of the tRNA. Details of ribosome structure not related directly to tRNA function will be ignored as much as possible. For example, we shall stress what happens to a tRNA when it binds to a ribosome, but not what happens to the ribosome. Almost all examples will be drawn from Escherichia coli. However, most generalizations probably apply accurately to other ribosomes.

The essential problem in studying tRNA-ribosome interactions is that far more is known about tRNA structure and dynamics than about ribosomes. The known structure and properties of tRNAs raise numerous interesting questions about how tRNA may function on the ribosome. However, it seems far easier to frame such questions than to design definitive experimental approaches for answering them. Some of the most powerful techniques available for the study of an isolated tRNA cannot be used on tRNA-ribosome complexes because of their large size, heterogeneity, and instability. The situation is analogous to the study of enzyme-substrate interactions in the absence of crystals of the enzyme-substrate complex. One has to hope that available knowledge about the substrate will be applicable...

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