Topology of membrane proteins

Integral membrane proteins play important roles in living cells. Due to dif ficulties of experimental techniques, theoretical approaches, i.e., topolog y prediction methods, are important for structure determination of this cla ss of proteins. Here we show a detailed comparison of transmembrane topolog y prediction methods. According to this comparison, we conclude that the to pology of integral membrane proteins is determined by the maximum divergenc e of the amino acid composition of sequence segments. These segments are lo cated in different areas of the cell, which can be characterized by differe nt physicochemical properties. The results of these prediction methods comp ared to the X-ray diffraction data of several transmembrane proteins will a lso be discussed.