CHAPTER 5 - Transfer RNA and Regulation at the Translational Level

Abstract

This chapter presents the transfer RNA and regulation at the translational level. Regulatory mechanisms at the level of mRNA translation could lead to gross metabolic changes. Changes in each of these components—ribosomes, factors involved in the ribosomal binding of messenger RNA (mRNA), in the initiation and termination of protein synthesis, and in polypeptide chain elongation, tRNA, and the components responsible for its acylation and subsequent transfer to the polysomal complex—could potentially lead to alteration in the rate, extent, or fidelity of protein synthesis. The central position occupied by the adaptor molecule tRNA in the protein synthetic mechanism, together with the known degeneracy of the genetic code and the multiplicity of the corresponding tRNA molecules makes this a likely candidate as a mediator of an ordered regulatory system. The constant refinement of techniques for the isolation of pure tRNAs and the methods available for the elucidation of tRNA sequences should help to rule out such errors primarily by permitting the rapid determination of the chemical and physical nature of observed changes. It is unclear in a majority of studies whether such differences relate to the synthesis of tRNA or to the destruction or modification of existing tRNAs. Studies of changes in cell tRNA population may be complemented by similar studies of the tRNA population being used for protein synthesis under various circumstances. Thus, by an equating of observed differences with specific functional changes in tRNAs, or with certain metabolic consequences, a potential role for certain tRNAs in the regulation of protein synthesis might be envisaged.