BLAST programs


BLAST programs search for term

BLAST is a family of programs (all included in the blastall executable). These include: Nucleotide-nucleotide BLAST (blastn) This program, given a DNA query, returns the most similar DNA sequences from the DNA database that the user specifies; Protein-protein BLAST (blastp) This program, given a protein query, returns the most similar protein sequences from the protein database that the user specifies; Position-Specific Iterative BLAST (PSI-BLAST) This program is used to find distant relatives of a protein. First, a list of all closely related proteins is created. These proteins are combined into a general profile" sequence; Position-Specific-Iterative BLAST (PSI-BLAST) This program is used to find distant relatives of a protein. First, a list of all closely related proteins is created. These proteins are combined into a general "profile" sequence, which summarises significant features present in these sequences. A query against the protein database is then run using this profile, and a larger group of proteins is found. This larger group is used to construct another profile, and the process is repeated. By including related proteins in the search, PSI-BLAST is much more sensitive in picking up distant evolutionary relationships than a standard protein-protein BLAST; Nucleotide 6-frame translation-protein (blastx): This program compares the six-frame conceptual translation products of a nucleotide query sequence (both strands) against a protein sequence database; Nucleotide 6-frame translation-nucleotide 6-frame translation (tblastx): This program is the slowest of the BLAST family. It translates the query nucleotide sequence in all six possible frames and compares it against the six-frame translations of a nucleotide sequence database. The purpose of tblastx is to find very distant relationships between nucleotide sequences; Protein-nucleotide 6-frame translation (tblastn) This program compares a protein query against the all six reading frames of a nucleotide sequence database; Large numbers of query sequences (megablast): When comparing large numbers of input sequences via the command-line BLAST, "megablast" is much faster than running BLAST multiple times. It concatenates many input sequences together to form a large sequence before searching the BLAST database, then post-analyze the search results to glean individual alignments and statistical values. (wikipedia)