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How to search for a protein sequence of an specific taxa in NCBI?

My example: Sequence of HBB (Hemoglobin Beta) in Fishes.

How can I do a good search to obtain above sequences?

sequence alignment ncbi

2 answers

NCBI Home --> Search for "Haemoglobin beta" --> Select Proteins/DNA --> Results by taxon (right hand pane) --> Find the Fishes in the list/tree

Thank you. But assume that I don't know all fishes scientific name, and its a long list. what is the smarter way?

If you are not interested in particular fish and there are many you can add these filters to the left page under species (click on customize button)

--> type "fish" in search window and then select teleost, ray-finned, catilaginous, bony, puffer and lobe-finned fish, as fish types.

A search term would look like this: (haemoglobin beta[Protein Name] OR (haemoglobin[All Fields] AND beta[All Fields])) AND "cartilaginous fishes"[ORGN]

PS: You can also look at efetch utilities (http://www.ncbi.nlm.nih.gov/books/NBK25499/).

NCBI eutils solution based on genomax2's suggestion

esearch -db protein -query "fish[orgn] AND haemoglobin beta[Protein Name] OR (haemoglobin[All Fields] AND beta[All Fields]) AND animals[filter]"|efetch -format fasta

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