Figure 2.

Structure of the IMD of human IRSp53. (A) Stereo diagram of the electron density derived from the three-wavelength MAD experiment contoured at 0.8σ and superimposed with the refined model. Shown is the core segment of the IMD signature sequence (¹⁸⁹EERRR¹⁹³). Bonds and atoms are coloured according to atom type (yellow/grey: carbon; red: oxygen; blue: nitrogen). Selected residues are indicated in single letter code. Chains A and B are distinguished by the colour of the carbon bonds. (B) Two orthogonal views, parallel and perpendicular to the noncrystallographic two-fold axis, of the IMD dimer in ribbon and molecular surface representation. The ribbon diagrams are colour ramped blue to green (chain A) and yellow to red (chain B). The mutation sites are indicated for one of the monomers in single letter code, and the location of the IMD signature sequence is highlighted with side chains in grey. Vertical dashed lines indicate the core region of the dimer. N- and C-termini of chains A and B are indicated in italics. (C) Packing of the IMD dimer in the unit cell. (D) Structural superposition of the IMD dimer with the BAR domain dimer (grey) of amphiphysin (pdb: 1uru, (Peter et al, 2004)). Figures 2 and 3 were generated using RIBBONS (Carson, 1997), Swiss-PDB Viewer (Guex and Peitsch, 1997), O (Jones et al, 1991) and GRASP (Nicholls et al, 1991).