| Type: | Domain | Name: | GAT domain |
| Description: | The GAT domain is a region of homology of ~130 residues, which is found in eukaryotic GGAs (for Golgi-localized, gamma ear-containing ADP ribosylationfactor (ARF)-binding proteins) and vertebrate TOMs (for target of myb). The GAT domain is found in its entirety only in GGAs, although, at the C terminusit shares partial sequence similarity with a short region of TOMs. The GAT domain is found in association with other domains, such as VHS and GAE. The GAT domain of GGAs serves as amolecular anchor of GGA to trans-Golgi network (TGN) membranes via its interaction with the GTP-bound form of a member of the ARF family of smallGTPases and can bind specifically to the Rab GTPase effector rabaptin5 and to ubiquitin [, , , ].The GGA-GAT domain possesses an all alpha-helical structure, composed of four helices arranged in a somewhat unusual topology, which has been called thehelical paper clip. The overall structure shows that the GAT domain has an elongated shape, in which the longest helix participates in twosmall independent subdomains: an N-terminal helix-loop-helix hook and a C- terminal three-helix bundle. The hook subdomain has been shown to be bothnecessary and sufficient for ARF-GTP binding and Golgi targeting of GGAs. The N-terminal hook subdomain contains a hydrophobic patch, which is found tointeract directly with ARF []. It has been proposed that this interactionmight stabilise the hook subdomain []. The C-terminal three-helix bundle isinvolved in the binding with Rabaptin5 and ubiquitin []. | Short Name: | GAT_dom |
