In bioinformatics, BLAST (Basic Local Alignment Search Tool) is an algorithm for comparing primary biological sequence information, such as the amino-acid sequences of different proteins or the nucleotides of DNA sequences. A BLAST search enables a researcher to compare a query sequence with a library or database of sequences, and identify library sequences that resemble the query sequence above a certain threshold. Different types of BLASTs are available according to the query sequences. For example, following the discovery of a previously unknown gene in the mouse, a scientist will typically perform a BLAST search of the human genome to see if humans carry a similar gene; BLAST will identify sequences in the human genome that resemble the mouse gene based on similarity of sequence.

Altschul,S.F., Gish,W., Miller,W., Myers,E.W. and Lipman,D.J. (1990) Basic local alignment search tool. J. Mol. Biol., 215, 403–410.

BLAST Search

Search for one or more of your sequences (using BLAST). First pick a query type (nucleotide or protein). You will be able to set search parameters on the next page. Choose the appropriate program based on the Query type and Target database type. Please click on the program name to view the search form.

Query Type Database Type BLAST Program
Nucleotide Nucleotide blastn: Search a nucleotide database using a nucleotide query.
Protein blastx: Search protein database using a translated nucleotide query.
Protein Nucleotide tblastn: Search translated nucleotide database using a protein query.
Protein blastp: Search protein database using a protein query.