Role of RNA Structure in RNA Editing

Abstract

The coding sequences of some mRNAs and the structures of some tRNAs and rRNAs in a variety of organisms are altered by posttranscriptional reactions termed editing; this can involve the modification or insertion/deletion of nucleosides. In this review, we focus on the role of RNA structure in three types of editing reactions that are known to alter the coding sequences of mRNAs: a cytosine deamination required for apoB-48 synthesis, an adenosine deamination required in some of the mammalian glutamate receptor subunits and also during the life cycle of the hepatitis delta virus, and the uridine insertion and deletion reactions needed to create functional open reading frames in many of the mitochondrial transcripts in the trypanosomatids. Although the contribution of RNA structure to these various types of RNA editing is just beginning to be understood, we attempt to summarize some of the recent advances in this field.

C TO U SUBSTITUTION EDITING IN THE APOLIPOPROTEIN B mRNA
Background
Apolipoprotein B (apoB) is a major protein of plasma lipoproteins and exists in two forms, apoB-100 and apoB-48 (Kane et al. 1980). In mammals, apoB-100 (512 kD) is synthesized in the liver. It is the ligand for the low-density-lipoprotein receptor and is also a component of very low density lipoproteins and intermediate-density lipoproteins (for review, see Chen et al. 1990). In contrast, apoB-48 (241 kD) is synthesized in the small intestine and is present in chylomicron and chylomicron remnants; apoB-48 is also produced by the liver in rodents (mice and rats) (for review,...