If you already have the sequence for a gene that you are interested in, use the blast. subdomain to identify homologous genes or regions across all assemblies in a GenomeHub.
This example searches for homologues of the Drosophila melanogaster acetylcholine esterase (Ace) gene FBgn0000024 in MealyBugBase.
1. Open the MealyBugBase SequenceServer instance at blast.mealybug.org:
2. Obtain the protein sequence of FBgn0000024 from FlyBase:
>FBpp0307210 MAISCRQSRVLPMSLPLPLTIPLPLVLVLSLHLSGVCGVIDRLVVQTSSGPVRGRSVTVQ GREVHVYTGIPYAKPPVEDLRFRKPVPAEPWHGVLDATRLSATCVQERYEYFPGFSGEEI WNPNTNVSEDCLYINVWAPAKARLRHGRGANGGEHPNGKQADTDHLIHNGNPQNTTNGLP ILIWIYGGGFMTGSATLDIYNADIMAAVGNVIVASFQYRVGAFGFLHLAPEMPSEFAEEA PGNVGLWDQALAIRWLKDNAHAFGGNPEWMTLFGESAGSSSVNAQLMSPVTRGLVKRGMM QSGTMNAPWSHMTSEKAVEIGKALINDCNCNASMLKTNPAHVMSCMRSVDAKTISVQQWN SYSGILSFPSAPTIDGAFLPADPMTLMKTADLKDYDILMGNVRDEGTYFLLYDFIDYFDK DDATALPRDKYLEIMNNIFGKATQAEREAIIFQYTSWEGNPGYQNQQQIGRAVGDHFFTC PTNEYAQALAERGASVHYYYFTHRTSTSLWGEWMGVLHGDEIEYFFGQPLNNSLQYRPVE RELGKRMLSAVIEFAKTGNPAQDGEEWPNFSKEDPVYYIFSTDDKIEKLARGPLAARCSF WNDYLPKVRSWAEFAQHITHVATSVFVYLKTWLISG
3. Paste the protein sequence into the text area at blast.mealybug.org and select databases to search:
4. Scroll to the bottom of the page to find the button to start the BLAST search. The appropriate BLAST algorithm (in this case BLASTP) will be selected automatically based on the type (protein or nucleotide) of the query sequence and databases selected. For users familiar with the command line versions of BLAST, a text box to the left of the BLAST button allows any additional parameters to be set. Click the button to start searching.
5. Once the search is complete, the view will change to show a summary of hits found in the target databases.
6. Click on the first sequence name in the Similar sequences table at the bottom of the screen to see more information (the order of hits may vary when following this tutorial):
7. Just under each sequence header is a row of links to view the sequence or alignment. The genomehubs link will take you directly to the associated record in the Ensembl browser at ensembl.mealybug.org:
