GTF (Gene Transfer Format, GTF2.2) is an extension to, and backward compatible with, GFF2. The first eight GTF fields are the same as GFF. The feature field is the same as GFF, with the exception that it also includes the following optional values: 5UTR, 3UTR, inter, inter_CNS, and intron_CNS. The group field has been expanded into a list of attributes. Each attribute consists of a type/value pair. Attributes must end in a semi-colon, and be separated from any following attribute by exactly one space.

The attribute list must begin with the two mandatory attributes:

Here is an example of the ninth field in a GTF data line:

gene_id "Em:U62317.C22.6.mRNA"; transcript_id "Em:U62317.C22.6.mRNA"; exon_number 1

The Genome Browser groups together GTF lines that have the same transcript_id value. It only looks at features of type exon and CDS.

For more information regarding the GTF2.2 UCSC supported format, see If you would like to obtain browser data in GTF format, please refer to our FAQ on GTF format or our wiki page on generating GTF or GFF gene file