Structure of the Mtss1 IMD-domain. A: Structural superposition of the IMD domain monomer from Mtss1 (PDB entry 2D1L) with that of IRSp53 (PDB entry 1Y2O; cf . 3D-structures were compared using the Vector Alignment Search Tool (VAST), and visualized with Cn3D 4.1. Alignment is color-coded (red, high), except for the region containing the nuclear localization signal, which is marked yellow to facilitate orientation. B: The putative nuclear localization signals (NLS; red, basic amino acids) in the IMD are marked on the chain of the IMD domain pointing to the left, whereas the putative export signal is marked white on the chain pointing to the right. Potential target sites for phosphokinases within/close to the NLS are marked green, whereas the remaining amino acids in the NLS are marked blue (see Fig 5B for sequence details). Panel B was generated using the SwissPDB viewer.