Figure 9
From: A PDB-wide, evolution-based assessment of protein-protein interfaces

Interface classification as a function of operator type. The green portions of the bars represent interfaces classified as bio, the red ones interfaces classified as xtal. Operators are denoted as follows, from left to right: 2S, two-fold screw axis; AU, non-crystallographic symmetry; XT, crystal cell translation; 2, two-fold axis; 3S, three-fold screw axis; 4S, four-fold screw axis; 3, three-fold axis; FT, fractional translation; 6S, six-fold screw axis; 4, four-fold axis; 6, six-fold axis; -1, inversion center; -4, four-fold rotoinversion axis; GL, glide plane.