BLAST Help
Available search programs
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blastn - Comparing a nucleotide query sequence
against a nucleotide sequence database.
blastp - Comparing an amino acid query sequence
against a protein sequence database.
blastx - Comparing a nucleotide query sequence translated
in all reading frames aginst a protein sequence database.
Parameters
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expect
Specify the expected number of homologous sequences
in the database. If you need to get more sequences
with lower homology score, increase the "expect" value.
If you need only sequences with very high homology scores,
decrease the value. [Real]
Default value: 10.0
filter
The server filters your query sequence for low compositional complexity
regions by default. Low complexity regions commonly give spuriously high
scores that reflect compositional bias rather than significant position-by- position
alignment. Filtering can elminate these potentially confounding matches
(e.g., hits against proline-rich regions or poly-A tails) from the blast reports,
leaving regions whose blast statistics reflect the specificity of their pairwise
alignment. Queries searched with the blastn program are filtered with DUST. Other
programs use SEG.
Low complexity sequence found by a filter program is substituted using the
letter "N" in nucleotide sequence (e.g., "NNNNNNNNNNNNN") and the letter "X"
in protein sequences (e.g., "XXXXXXXXX").
query_code (blastx only)
Specify Query Genetic code to be used in blastx translation
of the query.
Query genetic code table:
1 = Standard
2 = Vertebrate Mitochondrial
3 = Yeast Mitochondrial
4 = Mold Mitochondrial
5 = Invertebrate Mitochondrial
6 = Ciliate Macronuclear
9 = Echinodermate Mitochondrial
10 = Euplotid Nuclear
11 = Bacterial
12 = Alternative Yeast Nuclear
13 = Ascidian Mitochondrial
14 = Flatworm Mitochondrial
15 = Blepharisma Macronuclear
Default value: 1