Figure 2.

Crystal structure of PQIP–IGF1RK. (A) Ribbon diagram of the PQIP–IGF1RK crystal structure. PQIP is shown in stick representation with carbon atoms coloured yellow and nitrogen atoms coloured blue. An F_o–F_c omit map (PQIP omitted, followed by positional refinement) in the vicinity of PQIP is shown in purple mesh, calculated to 2.3 Å and contoured at 4σ. The N lobe of IGF1RK is coloured dark grey and the C lobe is coloured light grey. Within the N lobe, α-helix C (residues 1011–1026) is coloured pink and the nucleotide-binding loop (residues 978–981) is coloured blue. Within the C lobe, the activation loop (residues 1123–1144) is coloured green and the catalytic loop (residues 1103–1110) is coloured orange. The N and C termini of IGF1RK are indicated. (B) Stereo view of the interactions between PQIP and IGF1RK. IGF1RK residues that interact with PQIP are shown explicitly on the backdrop of a semitransparent ribbon diagram. Carbon atoms in IGF1RK are coloured according to the colouring scheme in (A), oxygen atoms are coloured red, nitrogen atoms are coloured blue and sulphur atoms are coloured green. An ordered water molecule is shown by a red sphere, and select hydrogen bonds are shown by dashed lines. (C) Schematic representation of the interactions of PQIP with IGF1RK residues. Residues (side chains, except for Gly1122 and Gly1125) making van der Waals (⩽3.9 Å) contacts with PQIP (coloured blue) are coloured according to the scheme in (A, B). Hydrogen-bonding interactions are represented by dashed lines. The red circle represents a water molecule. Figures 2, 3 and 4 were rendered using PyMOL (http://pymol.sourceforge.net).