Available QuickLook views of PDB files, using Jolecule. (a) Default cartoon view of a multi-chain protein complex, showing the two chains as different colours. (b) Zoomed view of a protein active site showing control of the z-slab, labelling of a selected residue and display of neighbouring residues as ball-and-stick representation. (c) Cartoon view of a protein–DNA complex, showing the two protein chains as red–brown and green and the DNA helix as blue and gold. (d) Overlay of Cα chains of two similar structures.