MODOMICS is a database of RNA modifications that provides comprehensive 
information concerning the chemical structures of modified ribonucleosides, 
their biosynthetic pathways, RNA-modifying enzymes and location of modified 
residues in RNA sequences. In the current database version, accessible at 
http://modomics.genesilico.pl, we included new features: a census of human and 
yeast snoRNAs involved in RNA-guided RNA modification, a new section covering 
the 5'-end capping process, and a catalogue of 'building blocks' for chemical 
synthesis of a large variety of modified nucleosides. The MODOMICS collections 
of RNA modifications, RNA-modifying enzymes and modified RNAs have been also 
updated. A number of newly identified modified ribonucleosides and more than one 
hundred functionally and structurally characterized proteins from various 
organisms have been added. In the RNA sequences section, snRNAs and snoRNAs with 
experimentally mapped modified nucleosides have been added and the current 
collection of rRNA and tRNA sequences has been substantially enlarged. To 
facilitate literature searches, each record in MODOMICS has been 
cross-referenced to other databases and to selected key publications. New 
options for database searching and querying have been implemented, including a 
BLAST search of protein sequences and a PARALIGN search of the collected nucleic 
acid sequences.