The model oriented on localization of areas responsible for ligand binding or protein-protein complex creation is based on characteristics of spatial distribution of hydrophobicity in a protein molecule: It is assumed that hydrophobicity changes from protein interior (maximal) to exterior (close to zero) according to the three-dimensional Gauss distribution (fuzzy oil-drop model). It is generally accepted that the core region is not well described by a spheroid of buried residues surrounded by surfaces residues due to hydrophobic channels that permeate the molecule. Therefore the simple comparison of theoretical (idealized according to Gauss function) and empirical spatial distribution of hydrophobicity in protein gives the opportunity to identify the regions with high deviation versus the ideal model. Those regions recognized by high hydrophobicity density discrepancy seem to reveal functionally important sites in proteins.