Modified Nucleosides in Translation

Cellular physiology is fundamentally dependent on the functions of translational apparatus, and these functions are dependent on modified nucleosides. This chapter examines the translational functions of modified nucleosides in the anticodon arm of tRNA. There are modifications at other positions within tRNA, but our knowledge of translational effects is limited to the modifications in the anticodon region. Emphasis is placed on the effects that the loss of specific modifications has on the activities of tRNA. Before considering the effects of modifications on translation, it is helpful to review certain aspects of the decoding process. Further work on the translational mechanism is needed to fully understand the roles of modified nucleosides in the important cellular process. The chapter discusses the effects of modified nucleosides at various positions in the anticodon arm. There are data on the translational effects of a subset of the modified nucleosides that occur within the anticodon arm. The chapter talks about a discussion of unmodified U34 because models for decoding by the modified forms are extended from those for unmodified U. Virtually all tRNAs contain modified nucleosides within the anticodon region, and it has become abundantly clear that they contribute to translation in a number of ways. The future looks very promising for the continued study and understanding of the roles that modified nucleosides play in the fundamentally important translational process.