The National Center for Biotechnology Information (NCBI) currently supports two versions of BLAST free of charge: BLAST 2.0 (gapped BLAST) and Position-Specific Iterated BLAST (PSI-BLAST). BLAST 2.0 is the standard version of BLAST, which allows a user to search a sequence database with a nucleotide or protein sequence of interest. BLAST 2.0 places gaps into the query and target sequences so that separate areas of similarity between the two sequences can be returned as one hit. PSI-BLAST is an iterative BLAST search, which is optimized for finding distantly related sequences.
Other BLAST programs are also available from the NCBI Web page. "BLAST 2 sequences" uses the BLAST search engine to produce an alignment of two sequences entered by the user. On the Specialized BLAST pages, researchers can use the BLAST engine to search sequences that are not in GenBank. At present, these databases include unfinished microbial genomes, P. falciparum (the human malaria parasite), and tentative
Contributed by Tyra G. Wolfsberg and Thomas L. Madden
Current Protocols in Protein Science (1999) 2.5.1-2.5.29 Copyright © 1999 by John Wiley & Sons, Inc.
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