BLAST

BLAST ( Basic Local Alignment Search Tool) comes under the category of homology and similarity tools. It is a set of search programs designed for the Windows platform and is used to perform fast similarity searches regardless of whether the query is for protein or DNA. Comparison of nucleotide sequences in a database can be performed. Also a protein database can be searched to find a match against the queried protein sequence. NCBI has also introduced the new queuing system to BLAST (Q BLAST) that allows users to retrieve results at their convenience and format their results multiple times with different formatting options. Depending on the type of sequences to compare, there are different programs: 1. blastp compares an amino acid query sequence against a protein sequence database 2. blastn compares a nucleotide query sequence against a nucleotide sequence database 3. blastx compares a nucleotide query sequence translated in all reading frames against a protein sequence database 4. tblastn compares a protein query sequence against a nucleotide sequence database dynamically translated in all reading frames 5. tblastx compares the six-frame translations of a nucleotide query sequence against the six-frame translations of a nucleotide sequence database.