*4.7. Residue–Residue Distances*

For the ECs being in direct atomic contact according to the Protein Contacts Atlas, the shortest atomic contact distance (between heavy atoms) has been accepted as residue–residue distance. For the rest of the ECs, the shortest distance between the heavy atoms of the two residues has been measured using PyMOL (https://pymol.org/2/; The PyMOL Molecular Graphics System, Version 2.0 by Schrödinger, LLC, New York, USA). Then, for each EC we have randomly selected an interface IDP residue and an interface partner residue from the same interface, and measured their distance similarly. The distances of ECs and the thereby assembled equivalent random reference interface pairs have been compared by Mann–Whitney U test. To check if the observed difference remains consistent, we have obtained 100 additional samples of random residue pairs and compared their distances to those of ECs.
