/usr/share/genometools/gtdata/trans/TransProt3 is in genometools-common 1.5.1-2ubuntu1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 | # 3-character structural alphabet
# A (ambivalent), E (external), I (internal)
ACGPSTWY A
RNDQEHK E
ILMFVJ I
XUBZO*- X
|