Figure 1

DIX domain structure. (A) Architecture of the DIX domain containing proteins Dishevelled, Axin and DIXdc1. Dishevelled has a N-terminal DIX domain, a PDZ and DEP domain. Axin has a RSG domain and C-terminal DIX domain. DIXdc1 has a coiled-coil domain and a C-terminal DIX domain. (B) The β-grasp fold structure of the Axin DIX domain, a β-sheet against which is packed a α-helix (1WSP). (C) Topology of the Axin DIX domain (blue) and ubiquitin (green). The ubiquitin-like β-grasp fold of both proteins consists of a 5-stranded β-sheet in which the strands are arranged in a 2-1-5-3-4 order starting at the protein N-terminus. In ubiquitin an additional helix, helix α2, connects strand β4 with strand β5. In Axin this helix is absent.