Detecting a stealth anthrax toxin gene The truth behind Blast
...but the protein sequence tells a different story
Now you are flabbergasted! How is it that searching
for similar DNA sequences yields no significant similarity to lef
but searching for protein sequences gives you perfect identity! Something
must be real funny with this DNA sequence, so you compare it by hand with the
corresponding DNA sequence from lef, getting the alignment shown here.
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sample protein
...TATLGADLVDS...
...TATLGADLVDS...
toxin protein
... Perfect identity!
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Things are not getting any clearer. The gene fragment
is highly similar to lef, about 90% identical. That's consistent
with the identity of the protein sequences, BUT THEN WHY DIDN'T BLAST FIND THE
DNA SEQUENCE??? In desperation, you compare the two DNA sequences by pairwise
Blast. Of course, you already know the answer -- you just did the same comparison by hand. You just want to see if Blast has gone crazy.
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