Figure 1
Structure of galectin-4N.
(A) Simulated annealing omit map of the calcium-binding site (engaging the S4–S5 loop) of the galectin-4N CRD with bound lactose. Galectin-4N CRD displayed as green cartoon representation with calcium- and lactose-binding site residues depicted in green sticks. Calcium ion is shown as a magenta sphere, its coordinating waters (red spheres) and the bound lactose molecule (stick model with carbon atoms in yellow). The S4–S5 loop cartoon and carbons are highlighted in lime green. Dashed lines highlight calcium coordination with its surroundings. The 2|Fo| − |Fc|αcalc map is illustrated in blue mesh at a 1.0 σ contour level and the |Fo| − |Fc|αcalc map is illustrated in red mesh at a 3.0 σ contour level. The omit map was created by Phenix. (B) Galectin-4N CRD shown in cartoon representation (β-strands (green), α-helical turn (red), loops (yellow)) with bound lactose molecule in stick representation (yellow carbons, red oxygens). The β-strands on the concave side of the β-sandwich and certain loops are labelled in black. Binding sub-sites are labelled in red. (C) Stereo image of galectin-4N CRD with side-chains of residues implicated in recognition of oligosaccharides displayed in stick representation (carbon (green) oxygen (red), nitrogen (blue)). Bound lactose molecule in transparent stick representation (carbon (yellow), oxygen (red)) indicates the conserved carbohydrate-binding site.
