Problems and Prospects in the Characterization of Posttranscriptional Modifications in Large RNAs

Abstract

The central importance of RNA in biology derives principally from the key functions of four RNAs at and in the ribosome, at the precise sites of decoding the genetic message and of peptide bond formation: transfer RNA (tRNA), messenger RNA (mRNA), small subunit ribosomal RNA (16S–18S rRNA), and large subunit ribosomal RNA (23S–28S rRNA). Rapidly accumulating evidence for direct participation of the rRNAs in translation [1, 2] has led to a remarkable reversal of fortune: protein synthesis is largely under control of specific domains of rRNA rather than of ribosomal proteins as originally thought. This has left rRNA relatively understudied with regard to the three-dimensional structure of the ribosome, and the precise roles of single rRNA nucleotides in the complex mechanism of translation.