As a shortcut, we will use the Entrez "Gene" database to quickly access the amino acid sequence of a gene product. The amino acid sequence also could be obtained by searching protein sequence databases such as NCBI's Entrez; this process, however, can be more involved and rather time consuming since it often requires examining and sifting through several sequence records.

To begin, go to the Entrez Gene site at NCBI:

Click on the image to see full-size!	Enter the gene symbol in the search box at the top of the Entrez Gene page, then click on "GO". Records will be retrieved for the hemochromatosis gene in humans as well as mouse (Mus musculus), Norway rat (Rattus norvegicus), cow (Bos taurus), etc.  NOTE: The field qualifier [sym] can be used to limit the search by gene symbol only. Since a gene symbol is unique for each human gene, you should retrieve only one result. For more information on options for refining your search, follow the link in the sidebar to the "Gene Handbook". Click on the link for the human HFE protein.
k on the image to see full-size!	The Summary section. This section provides basic information about the gene, such as its symbol, alternative symbols (aliases), species, lineage, etc. Perhaps the most informative line is the "Summary" which discusses the structure and function of the protein, its role in disease, its inheritance, and the molecular defects which are known.
Click on the image to see full-size!	The Genomic region, transcripts and products section.  The graphic in this section depicts 11 different isoforms of the HFE gene. The longest isoform is at the top. Note that all the remaining isoforms carry deletions in either the 5' UTR, an exon, or a 3' UTR.  For example:  isoform 4 is missing exon 2 and part of the 3' UTR isoform 3 carries all four exons, but is missing most of the 5' UTR and all the 3' UTR. Links to the RefSeq nucleotide records for each isoform are to the left of each graphic. Links to the RefSeq protein records for each isoform are to the right of each graphic.
The Genomic context section.  This section provides information about the locus of the gene.  The cytogenetic locus of the human HFE gene is in band 21.3 on the short arm of chromosome 6. The graphic gives additional information at finer resolution. In this case the HFE gene is located between 3 genes for histidine biosynthesis. The accession number in the Protein database for isoform 1 is NP_000401 (indicated by the oval in the graphic above).  Click on this link to open the record.
Click on the image to see full-size!	The protein database contains sequence data from the translated coding regions from DNA sequences in GenBank, EMBL and DDBJ, as well as protein sequences submitted to Protein Information Resource (PIR), SWISS-PROT, Protein Research Foundation (PRF), and Protein Data Bank (PDB). The flat file format of the Protein database is the same as for nucleotide sequences in GenBank. However the data in each record can also be displayed in numerous other formats, including the FASTA format. Open the pull-down "Display" menu, and click on "FASTA"
Click on the image to see full-size!	A record in FASTA format begins with a one-line description, followed by the sequence.  The description line begins with a “>” symbol, followed by a one-word identifier (in this case >gi|4504377|ref|NP_000401.1).  The rest of the line contains additional information.  The second line, and all others, contain the sequence. Blank lines in a FASTA file are ignored, and so are spaces or other gap symbols (dashes, underscores, periods) in a sequence. Open the pull-down “Send To”  menu and click on “File”. Using the dialog box which appears, save the sequence in FASTA format to your desktop.

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