The ubiquitous hammerhead ribozyme.

The hammerhead ribozyme is a small catalytic RNA motif capable of endonucleolytic (self-) cleavage. It is composed of a catalytic core of conserved nucleotides flanked by three helices, two of which form essential tertiary interactions for fast self-scission under physiological conditions. Originally discovered in subviral plant pathogens, its presence in several eukaryotic genomes has been reported since. More recently, this catalytic RNA motif has been shown to reside in a large number of genomes. We review the different approaches in discovering these new hammerhead ribozyme sequences and discuss possible biological functions of the genomic motifs.