Figure 1.

Distance between domain pairs on a protein chain and the likelihood that they interact The solid line indicates the percentage of domain pairs, within a distance range apart, which are in contact. The broken line shows the distribution of chi-squared values corresponding to constructed 2 × 2 contingency tables that classified domain pairs according to 2 criterions; 1) whether or not they are separated by a distance no greater than the upper limit of each range, and 2) whether or not the domain pair is interacting. The percentage of interacting domain pairs drop noticeably after 30 residues, and the chi-squared value is also maximum at this threshold.