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The blast programs compare a given sequence (of amino acids or
nucleotides) with all the sequences of a database using the
statistical methods of Karlin and Altschul [Kar Al 90].
There are six blast applications: blastp, blastn, tblastn, blastx,
tblastx and blast3 which were implemented at NCBI:
- blastp: compares an amino acid query sequence against a protein
- blastn: compares a nucleotide query sequence against a
nucleotide sequence database.
- blastx: compares the six-frame conceptual translation products
of a nucleotide query sequence against a protein
- tblastn: compares a protein query sequence against a nucleotide
sequence database dynamically translated in all six reading frames.
- tblastx: compares the six-frame translations of a nucleotide
query sequence against the six-frame translations of a nucleotide
- blast3: compares an amino acid query sequence against a protein
sequence database and identifies statistically significant three-way
sequence alignments in which the component pairwise alignments are
What is a six-frame translation? For our purpose it is enough, if we
say, that it is the mapping of nucleotide sequences to amino acid sequences
in 6 possible ways.
Blast3 exists in version 1.3, but not in 1.4, so we did not parallelize
Compte de groupe
Fri Jan 20 15:43:12 MET 1995