BLAST Search tool

BLAST Basic local alignment search tool

1. BLAST Kishan Sharma M.Sc. 2 nd Year Biotechnology Manipal University Jaipur

2. BLAST B asic L ocal A lignment S earch T ool It is a sequence similarity search program for comparing biological sequences such as amino acid sequence of different proteins or the nucleotides of DNA sequences with sequence database or library sequences.

3. BLAST BLAST was designed by Eugene Myers , Samuel Karlin , Stephen Altschul , Warren Gish, David J. Lipman and Webb Miller at the National Institute of Health and was published in Journal of Molecular Biology in 1990. It was originally developed & controlled by NCBI . Link: http://www.ncbi.nlm.nih.gov/BLAST/

4. BLAST Sequence alignments provide a powerful way to compare sequences with previously characterized genes. Both functional and evolutionary information can be inferred from well designed queries and alignments. The BLAST detects local as well as global alignments and regions of similarity in unrelated proteins can be detected.

5. BLAST

6. BLAST types Blastp : compares protein query against proteins sequence database. tBlastn : Compares a protein query sequence against a nucleotide sequence database. Blastn : compares nucleotide query against nucleotide sequence database.

7. BLAST types Blastx : Compares a nucleotide query sequence translated in all reading frames against a protein sequence database. This option may be used to find potential translation products of an unknown nucleotide sequence. tBlastx : compares nucleotide query against translated nucleotide sequence database.

8. BLAST All BLAST programs use a substitution scoring matrix (BLOSUM or PAM), determines pair-wise alignment scores. BLAST finds homologous sequences , not by comparing either sequences in its entirety, but rather by locating short matches between the two sequences.

9. NCBI Home page

10. NCBI-BLAST Home Page

11. Applications of BLAST Identifying Species: With the use of BLAST, you can possibly correctly identify a species and/or find homologous species. This can be useful, for example, when one is working with a DNA sequence from an unknown species. Establishing Phylogeny: Using the results received through BLAST, one can create a phylogenetic tree using the BLAST web-page.

12. Applications of BLAST DNA Mapping: When working with a known species, and looking to sequence a gene at an unknown location, BLAST can compare the chromosomal position of the sequence of interest, to relevant sequences in the database. Locating Domains: When working with a protein sequence you can input it into BLAST, to locate known domains within the sequence of interest . Comparison: When working with genes, BLAST can locate common genes in two related species, and can be used to map annotations from one organism to another.

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