Search for sequence similarity with the help of BLAST

Search for sequence similarity with the help of BLAST

Program set BLAST for searching similarity of sequences is a perfect alternative to text search in Entrez system. By using BLAST for new sequences, homologues of known sequences can be found quickly. Further links of these homologous sequences allow fluent navigation in Entrez system.

BLAST search system is presented in the websitehttp://www.ncbi.nlm.nih.gov/BLAST/. Query window allows selecting organism type, database and BLAST algorithm for conducting search. The main BLAST methods are as follows:

nucleotide blast Search a nucleotide database using a nucleotide query
protein blast Search protein database using a protein query
blastx Search protein database using a translated nucleotide query
tblastn Search translated nucleotide database using a protein query
tblastx Search translated nucleotide database using a translated nucleotide query

BLAST search results are presented in descending homology order, so that conservative sequence domains could be identified in one window (Picture 3). Each sequence is an active link to relevant database which in addition to the sequence in question and homology results, also provides further links to other database such as Entrez Gene, Entrez Protein and so on.


Picture 3. BLAST search results