3D Complex: A Structural Classification of Protein Complexes
Figure 5
Redundancy in the Protein Data Bank at Several Levels of Sequence Similarity
(A) The number of structures at each level of the 3D Complex database, from 192 QSTs to the total number of structures in the PDB (21,037). The tick marks on the line below the graph indicate the consecutive pairs of levels that are plotted in (B–E).
(B) Number of QS30 per QS. Note that QS Families are almost identical to QSs. The first bar in the histogram shows that about 2,500 QS correspond to one QS30; the second bar represents 250 QS that correspond to two QS30.
(C) Number of QS90 per QS30.
(D) Number of QS100 per QS90.
(E) Number of complexes in the complete set per QS100.
All distributions display scale-free behaviour, in the sense that a large proportion of groups are identical at any two consecutive levels, whereas a small number are very redundant. Adding symmetry information does not change this trend, as shown in Table 1.