NetBlastP

Input
Remote DataBase   Remote DataBase selection:
Non-Redundant - All Non-Redundant GenBank CDS translations, PDB, SwissProt, PIR and PRF. Non-Redundant.
SwissProt DB - Last major release of the SWISS-PROT protein sequence database (no updates).
Patent Protein Sequence (PAT) - Patent Protein Sequence database.
PDB Records - Sequences derived from the 3-Dimensional structure records from PDB.
Monthly Sequences (Month) - All new or revised GenBank CDS translations, PDB, SwissProt, PIR and PRF released in the last 30 days.
Custom - Specify the database of your interest.
Nucleotide Query sequence(s)   If the input file contains multiple sequences, BLAST will be run on each sequence in order, and the resulting output will contain concatenated BLAST reports.
Believe the query defline.   Believe the query definition line.
Output
Result   Designates an output file for the search results.
Format   Pairwise (Default)
Query-anchored, showing identities
Query-anchored, no identities
Flat query-anchored, showing identities
Flat query-anchored, no identities
Query-anchored, no identities and blunt ends
Flat query-anchored, no identities and blunt ends
XML Blast output
Tabular
Tabular with comment lines
ASN, text
ASN, binary
Show GI's in deflines  Shows GenInfo Identifier (GI) numbers in definition lines.
A GI is a unique numeric identifier assigned for a sequence in GenBank.
A GI corresponds to an accession version pair.
Produce HTML output   Produces HTML output with [anchor] links from the summary at the top of the report to the alignments farther below.
This option should be used only with the standard report format ("Pairwise (Default)").
Options
Expectation value   Sets the threshold expectation value for keeping alignments.
This is the E from the Karlin-Altschul equation that describes how often an alignment with a given score is expected to occur at random.
Filter query sequence   Filters the query sequence for low-complexity subsequences.
The default setting is ON.
Complexity filtering is generally a good idea, but it may break long HSPs into several smaller HSPs due to low-complexity segments.
This can cause some alignments to fall below the significance threshold and be lost. To prevent this, either turn off filtering (not recommended) or use soft masking, in which the filter is used only in the word seeding phase, but not the extension phase.
DUST with blastn, SEG with others.
Perform gapped alignment Performs gapped alignment.
Setting this to OFF invokes the older, ungapped style of alignment.
You can't perform gapped alignments with tblastx, regardless of this setting.
Open Gap Cost   Initial penalty for opening a gap of length 0. -1 invokes the default behavior, and setting the parameter to zero is impossible, unless the "Perform gapped alignment" option is set to NO, which turns gapping off. The default gap costs for programs other than blastn depend on the scoring matrix.
Extend Gap Cost  The penalty for each gap character. Note that value -1 is synonymous with the default behavior for the "Open Gap Cost" parameter and, it's impossible to set value to zero unless the "Perform gapped alignment" option is set to NO, which turns gapping off. The default gap cost, for programs other than blastn, depends on the scoring matrix.
Matrix   Designates a protein similarity matrix.
This is used in all BLAST programs except blastn.
Matrices are sought in the following order: in the local directory, in the location specified in the .ncbirc file, in a local data directory, and finally, in the BLASTMAT environment variable (only on Unix systems). Other matrices included in the standard distribution include BLOSUM45, BLOSUM80, PAM30, and PAM70.
You can use custom matrix files, but it requires modifying the source code and defining the new matrix with all of its associated statistics for different affine gap combinations and recompiling the binary. Using these custom files isn't recommended because it requires the arduous task of calculating gapped values for lambda and maintaining a derivative branch of the source code.
Query strands   Chooses which strand of DNA-based queries is searched.
Top Strand
Bottom Strand
Both Strands
Location on query sequence   The location on query sequence.
This lets you limit the search to a subsequence of the query sequence.
For example, to search just the letters from 21 to 50, set the parameter to following: "21,50".
The alignments won't extend outside the specified region.
In older versions of BLAST, this parameter set the size of the region under control of the "Best Hits Number" parameter.
Search Space Effective Length   Effective length of the search space. Use zero for the real size (Default).
Lower Case Filtering   Use lower case filtering of FASTA sequence.
Ungapped Extension X dropoff value   X dropoff value for ungapped extensions in bits;
Zero invokes default behavior; blastn 20, megablast 10, all others 7.
Final Gapped Alignment X dropoff value   X dropoff value for final gapped alignment in bits;
Sets the X3 dropoff value (in bits) for extensions but is bounded by the value for X2.
Zero invokes default behavior; blastn/megablast 50, tblastx 0, all others 25.