Which one of these are you referring to?
ATG may refer to:
ATG, the triplet code for the amino acid methionine
Anti-thymocyte globulin, antibodies to prevent and treat transplant rejection
ATG Stores, an e-tail site
Antigua and Barbuda, using its ISO 3166-1 alpha-3 country code
Alexander the Great, king of Macedon, in northern Greece
Adhesive Transfer Gun, the formal name for a tape gun
Advanced Technology Group (Apple), a former division of Apple Computer
Advanced Technology Group (Novell), a former division of Novell
Aktiebolaget Trav och Galopp, the horse betting monopoly in Sweden
Alaska Territorial Guard, a military reserve force in World War II
Alternative Tourism Group, a Palestinian NGO
Ambassador Theatre Group, a theatre group in the UK
Ankara Tren Garı, a railway station in Ankara, Turkey used exclusively for high-speed rail.
Anti-tank gun, a mobile weapon used against armoured vehicles
Anti Tank Guitar, a string instrument
Art Technology Group, a software developer
Art Theatre Guild, a Japanese film production company
At the Gates, a melodic death metal band
Autophagy gene, gene coding for protein that facilitates autophagy (catabolic breakdown of unneeded or dysfunctional cellular constituents).
Aviation Technology Group, the defunct developer of the Javelin Very Light Jet (VLJ)
Auto-gating in night vision devices