The hydrophobic patch and binding of cadmium ions. A. Mapping the locations of the residues that form the hydrophobic patch (Leu-8, Ile-44, and Val-70) with respect to the crystallographic dimer interface in four Ub crystal structures. Chain A are shown in green and chain B in cyan. Residues from the hydrophobic patch are shown as red sticks and labelled. When present, cadmium ions are shown as either green or cyan spheres, according to the Ub monomer they bind to. B. The five cadmium binding sites observed. Residues of chain A are in green while symmetry related molecules are shown in different colours. Contacts between cadmium ions (red spheres) and water molecules (magenta spheres) are indicated by dashed lines, with the corresponding distances labelled in Å. Oxygen atoms are coloured in red and nitrogen atoms in blue.