PROSITE documentation PDOC50909

GAT domain profile

The GAT domain is a region of homology of ~130 residues, which is found in eukaryotic GGAs (for Golgi-localized, γ ear-containing ADP ribosylation factor (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-terminus it shares partial sequence similarity with a short region of TOMs. The GAT domain is found in association with other domains, such as VHS (see <PDOC50179>) and GAE (see <PDOC50180>). The GAT domain of GGAs serves as a molecular 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 small GTPases and can bind specifically to the Rab GTPase effector rabaptin5 and to ubiquitin [1,2,3,4,5].

The GGA-GAT domain possesses an all α-helical structure, composed of four helices arranged in a somewhat unusual topology, which has been called the helical paper clip (see <PDB:1NAF>). The overall structure shows that the GAT domain has an elongated shape, in which the longest helix participates in two small independent subdomains: an N-terminal helix-loop-helix hook and a C-terminal three-helix bundle. The hook subdomain has been shown to be both necessary and sufficient for ARF-GTP binding and Golgi targeting of GGAs. The N-terminal hook subdomain contains a hydrophobic patch, which is found to interact directly with ARF [3]. It has been proposed that this interaction might stabilize the hook subdomain [4]. The C-terminal three-helix bundle is involved in the binding with Rabaptin5 and ubiquitin [5].

The profile we developed covers the entire GAT domain.