BLAST

BLAST is a 'basic local alignment search tool', an algorithm used to compare primary biological sequences, such as the nucleotides of DNA or RNA sequences or amino-acid of protein. A BLAST search allows a scientist to compare the protein or nucleotide sequences with a database of sequences and detect database sequences similar to the query sequence.

BLAST is a family of programs. These comprise: (i) Nucleotide-nucleotide BLAST (blast n): DNA sequences are submitted to the DNA database to find the most similar sequences; (ii) Protein-protein BLAST (blast p): similar to blast n, protein sequences are submitted to the database to identify the most similar protein sequences from the protein database; (iii) Position-Specific Iterative BLAST (PSI-BLAST) (blast pgp): This program is applied to find distant relatives of a protein; (iv) Nucleotide 6-frame translation protein (blast x): This program compares a protein sequence database with the six-frame conceptual translation products of a nucleotide query sequence (both strands); (v) Nucleotide 6-frame translation-nucleotide 6-frame translation (t blast x): This program is applied to find the distant associations between nucleotide sequences; (vi) Protein-nucleotide 6-frame translation (t blast n): A protein query compares with reading frames of all six-nucleotide sequence databases in this program; (vii) Large numbers of query sequences (mega blast): This program compares large numbers of input sequences more rapidly than running BLAST multiple times. [Anwar Hossain]