GtRNAdb is a database of transfer RNA (tRNA) genes detected in genomic sequences. It contains over 74,000 tRNA genes predicted from 740 species. The database provides overview statistics of tRNA genes within each genome, including information by isotype and genetic locus, downloadable primary sequences, graphical secondary structures, and multiple sequence alignments. Direct links to UCSC genome browsers allow users to view tRNA genes in the context of other genetic information. The database can be searched by primary sequence similarity, tRNA characteristics, or phylogenetic group. It is publicly available at http://gtrnadb.ucsc.edu. The database was developed to catalog the increasing number of predicted tRNA genes found in complete genomes. It serves as a repository for all identifications made by tRNAscan-SE. The database has been in regular use for over 7 years and has been updated to improve its interface, content, and search capabilities. It provides summary statistics of predicted tRNA genes and the number of isotypes detected in each genome. Researchers can view tRNA genes by retrieving primary sequences, secondary structure information, and isotype alignments. Alternatively, tRNA genes can be viewed within the UCSC Genome Browser or similar microbial genome browsers. A new database search page and BLAST server enable similarity studies of tRNA genes across species. The database includes tRNA secondary structures and alignments. Although all mature non-organellar tRNAs form a general cloverleaf secondary structure, variations in the length of stem-loops exist. tRNAscan-SE provides highly accurate secondary structure predictions for each tRNA. These structures can be viewed in linear string representations or as graphical images. The database also provides multiple sequence alignments across all tRNAs of the same isotype within a species. These alignments are constructed via alignment to domain-specific tRNA covariance models. The database also provides a tRNA search and BLAST server. Researchers can use this tool for comparative analysis across multiple genomes. The search capabilities allow researchers to query the database with criteria including phylogenetic domain and clade, partial species name, chromosome or scaffold name, any combination of amino acids and anticodons, nucleotide identity at the -1 upstream position, number of introns, and the existence of a genome-encoded terminal CCA sequence. Search results can be downloaded for further analysis. The database also includes error and request tracking features, allowing users to submit reports and suggestions for new features. The database is designed for future expansion, with plans to provide more criteria for queries and allow specification of sequence patterns at multiple positions within tRNAs. Genes found via searches will be dynamically aligned with secondary structure information for comparative studies. Users can download gene information in various file formats, including BED and Stockholm formats. The database will continue to update with new tRNA identifications as additional genomes become available. It encourages members of the research community to request analyses of draft orGtRNAdb is a database of transfer RNA (tRNA) genes detected in genomic sequences. It contains over 74,000 tRNA genes predicted from 740 species. The database provides overview statistics of tRNA genes within each genome, including information by isotype and genetic locus, downloadable primary sequences, graphical secondary structures, and multiple sequence alignments. Direct links to UCSC genome browsers allow users to view tRNA genes in the context of other genetic information. The database can be searched by primary sequence similarity, tRNA characteristics, or phylogenetic group. It is publicly available at http://gtrnadb.ucsc.edu. The database was developed to catalog the increasing number of predicted tRNA genes found in complete genomes. It serves as a repository for all identifications made by tRNAscan-SE. The database has been in regular use for over 7 years and has been updated to improve its interface, content, and search capabilities. It provides summary statistics of predicted tRNA genes and the number of isotypes detected in each genome. Researchers can view tRNA genes by retrieving primary sequences, secondary structure information, and isotype alignments. Alternatively, tRNA genes can be viewed within the UCSC Genome Browser or similar microbial genome browsers. A new database search page and BLAST server enable similarity studies of tRNA genes across species. The database includes tRNA secondary structures and alignments. Although all mature non-organellar tRNAs form a general cloverleaf secondary structure, variations in the length of stem-loops exist. tRNAscan-SE provides highly accurate secondary structure predictions for each tRNA. These structures can be viewed in linear string representations or as graphical images. The database also provides multiple sequence alignments across all tRNAs of the same isotype within a species. These alignments are constructed via alignment to domain-specific tRNA covariance models. The database also provides a tRNA search and BLAST server. Researchers can use this tool for comparative analysis across multiple genomes. The search capabilities allow researchers to query the database with criteria including phylogenetic domain and clade, partial species name, chromosome or scaffold name, any combination of amino acids and anticodons, nucleotide identity at the -1 upstream position, number of introns, and the existence of a genome-encoded terminal CCA sequence. Search results can be downloaded for further analysis. The database also includes error and request tracking features, allowing users to submit reports and suggestions for new features. The database is designed for future expansion, with plans to provide more criteria for queries and allow specification of sequence patterns at multiple positions within tRNAs. Genes found via searches will be dynamically aligned with secondary structure information for comparative studies. Users can download gene information in various file formats, including BED and Stockholm formats. The database will continue to update with new tRNA identifications as additional genomes become available. It encourages members of the research community to request analyses of draft or