Pseudoknots: a new motif in the RNA game.

In the last few years a novel RNA folding principle called pseudoknotting has emerged. Originally discovered in noncoding regions of plant viral RNAs, pseudoknots now appear to be a widespread structural motif in a number of functionally different RNAs. These structural elements are part of tRNA-like structures and are involved in folding catalytic sites of ribozymes. They increase the efficiency of ribosomal frameshifting or can serve as specific binding sites for regulatory proteins.