.FAS File Extension
FASTA Sequence File
| Developer | David J. Lipman and William R. Pearson |
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A FAS file may also be a plain text file saved in the FASTA format, a file format used for storing nucleic acid and protein sequences. It contains one or more sequences, which include a sequence identification code and the sequence. Biochemistry students, academics, and professionals may use FAS files to store and process bioinformatics information, such as the genomes of different species.
More Information
David J. Lipman and William R. Pearson created the FASTA format and released it in 1985. It has since become a standard format for transferring sequences between applications because of its simplicity.
The FASTA format
The FASTA format is simple, consisting of the following elements:
- A line beginning with the > character, then followed by a sequence identification code. A text description of the sequence may follow the code, but this is optional, and the DNA software may ignore it.
- The next line is the sequence itself, which may be more than one line.
NOTE: FAS files may be saved with other file extensions, such as .fasta (.FASTA files) and .fa (.FA files), but they are saved in the same FASTA format.
How to open a FAS file
You can open an FAS file with various DNA applications, such as GSL Biotech SnapGene (multiplatform), Genome Compiler (multiplatform), and Heracle BioSoft DNA Baser (Windows). To open an FAS file with SnapGene, select .
Opening an FAS file with a text editor
Since FAS files are saved in plain text, you can also open them with a text editor, such as Microsoft Notepad (Windows) or Apple TextEdit (Mac), or a source code editor. Keep in mind that a text editor or source editor will not display the sequence in the FAS file natively like a DNA app. Also, you may need to rename the .fas file extension to .txt for the text editor to recognize it.
When opened in a text editor or source code editor, you can modify the properties of the FAS file, including the sequence. However, if you incorrectly edit the file, you may corrupt the sequence.
How to convert a FAS file
Several applications, including GSL Biotech SnapGene and Heracle BioSoft DNA Baser, can convert FAS files to other formats.
For example, SnapGene can convert FAS files to the following formats: