BLAST - Basic Local Alignment Search Tool

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Don’t confuse BLAST and Blast. BLAST is not an explosion. It is a tool of Bioinformatics. It stands for Basic Local Alignment Search Tool. As the name says, it is a similarity search tool in Bioinformatics and is the most effective and useful tool of Bioinformatics.

BLAST is a search tool based on the local alignment of two sequences. It is basically a similarity search tool. With this tool, we can easily check the similarity between two sequences. Many orthologous sequences can also be found by this tool. This tool is developed and maintained at NCBI (National Center for Biotechnology Information). It is an algorithm for comparing biological sequence information, either amino acid sequence or DNA sequence. BLAST was designed in 1990 by Eugene Myers, Stephen Altschul, Warren Gish, David J. Lipman and Webb Miller at NIH.

Since it is designed to address fundamental problems in bioinformatics, and its algorithm emphasis is more on speed rather than sensitivity, this program is most widely used in bioinformatics.

There are many versions of BLAST such as:

Blastn – this program, given a DNA query, returns the most similar DNA sequences from the DNA database that the user specifies. Blastp – this program, given a protein query, returns the most similar DNA sequences from the protein database that the user specifies. PSIBLAST – this program is used to find the distantly related proteins. PSI stands for Position Specific Iteration. First, a list of all the closely related proteins and then it combines them to a profile sequence. Now, they are checked for similarities in a protein database. Blastx – this program compares the six frame translation of DNA sequence with a protein database. Tblastx – this program compares the six possible frames with six frame translation of a DNA sequence. Tblastn – this program compares a protein sequence against the six frame translation of a nucleotide sequence database.

With these variations, BLAST performs many searches and its algorithm is also very good and accurate. Thus this tool is a very widely used tool in bioinformatics.