GB to FASTA conversion looks like a data transfer between two biochemistry formats (GenBank and Fasta). This conversion can probably be done using some dedicated utilities developed exactly for this purpose, or with some bio-analysis software.
Convert GenBank sequence record file to FASTA format DNA and protein sequence alignment.
We have found one software suitable in our database for this conversion.
Microsoft Windows software - convert gb to fasta on Windows
GenBank to Fasta Converter is a a freeware molecular biology tool that can convert GenBank (gb/gbk) file format to FASTA format.
Convert from gb file
to fasta file
The table with program actions contains information about what each program is capable of doing with their files. This may be a good pointer for further searches for certain file conversions and help you find the converter you are looking for if our search result is insufficient for you. However, it is far from perfect and may sometimes show results which are not really usable because of the nature of the software handles the files. So a conversion that appears as possible, just because of matched actions, may in fact not be possible.