Ribonuclease P is responsible for the 5'-maturation of tRNA precursors, Ribonuclease P is a ribonucleoprotein, and in bacteria the RNA subunit alone is catalytically active in vitro, i.e., it is a ribozyme. The Ribonuclease P Database is a compilation of ribonuclease P sequences, sequence alignments, secondary structures, three-dimensional models, and accessory information, available via the World Wide Web (http://www.mbio.ncsu.edu/RMaseP/home.html).