The BLAST family of
programs allows all combinations of DNA or protein query sequences with
searches against DNA or protein databases. (Most of the time use of these is
transparent, behind an interface.)
blastp: compares an amino acid query sequence against a protein sequence
database.
blastn: compares a nucleotide query sequence against a nucleotide sequence
database.
blastx: compares the six-frame conceptual translation products of a nucleotide query sequence (both
strands) against a protein sequence database.
tblastn: compares
a protein query sequence
against a nucleotide sequence database dynamically translated in all six reading
frames (both strands).
tblastx: compares
the six-frame translations of a
nucleotide query sequence
against the six-frame translations of a
nucleotide sequence
database.