NCBI

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A GENE NAME, PRODUCT NAME, OR SYMBOL

1. Search the Gene database with the gene name, symbol. If you know the gene symbol and species, enter them as follows: tpo[sym] AND human[orgn]
2. Click on the desired gene.
3. Click on Reference Sequences in the Table of Contents at the upper right of the gene record.
4. The NCBI Reference Sequences section of the record has links to NCBI curated records for transcripts (NM and XM prefix reference sequences) for the gene of interest for eukaryotic organisms. Transcript sequences are not produced for prokaryotes.
5. If there is no gene record for the organism and gene of interest, perform a search in the UniGene database with the gene name, product name, or symbol.
6. Click on the UniGene cluster of interest.
7. The UniGene cluster has links to transcript sequences for the gene from the Nucleotide and EST databases
8. If there is no UniGene cluster for this gene and organism, perform a search in the Nucleotide database with the gene name, product name, or symbol. Include the organism in the search to find the most relevant results and filter for transcript sequences, for example: Cytochrome c AND bullfrog[orgn] AND mrna[filter].

A NUCLEOTIDE OR PROTEIN SEQUENCE

1. Use the NCBI BLAST service to perform a similarity search.
2. For a nucleotide sequence select the nucleotide blast service from the Basic BLAST section of the BLAST home page. For a protein sequence, select the blastx translating service. The following databases contain transcript sequences: Reference mRNA (refseq_mrna), Nucleotide collection (nr/nt), and the EST databases.
3. Click the BLAST button to run the search and identify matching sequences.