| abstract |
canonical GAT domain found in eukaryotic ADP-ribosylation factor (Arf)-binding proteins (GGAs), metazoan myb protein 1 (Tom1)-like proteins, and similar proteins. This model represents the canonical GAT (GGA and Tom1) domain found in GGAs from eukaryotes, Tom1-like proteins from metazoa, and LAS seventeen-binding protein 5 (Lsb5p)-like proteins from fungi. The canonical GAT domain is a monomeric three-helix bundle that binds ubiquitin. GGAs, also called Golgi-localized gamma-ear-containing Arf-binding proteins, belong to a family of ubiquitously expressed, monomeric, motif-binding cargo/clathrin adaptor proteins that regulate clathrin-mediated trafficking of cargo proteins from the trans-Golgi network (TGN) to endosomes. GGAs play important roles in ubiquitin-dependent sorting of cargo proteins both in biosynthetic and endocytic pathways. Tom1 and its related proteins, Tom1L1 and Tom1L2, form a protein family sharing an N-terminal VHS-domain followed by a GAT domain. Tom1 family proteins bind to ubiquitin, ubiquitinated proteins, and Toll-interacting protein (Tollip) through its GAT domain. They do not associate with either Arf GTPases through its GAT domain nor with acidic cluster-dileucine sequences through its VHS domain. In addition, Tom1 family proteins recruit clathrin onto endosomes through their C-terminal region. The C-terminal clathrin-binding region of Tom1 and Tom1L2 are similar to each other, but distinguishable from Tom1L1. |