Application of protein grey incidence degree measure to predict protein quaternary structural types

Many proteins are composed of two or more subunits, each associated with different polypeptide chains. The number and arrangement of subunits forming a protein are referred to as quaternary structure. It has been known for long that the functions of proteins are closely related to their quaternary structure. In this paper the grey incidence degree is introduced that can calculate the numerical relation between various components, expressed the similar or different degree between these components. We have demonstrated that introduction of the grey incidence degree can remarkably enhance the success rates in predicting the protein quaternary structural class. It is anticipated that the grey incidence degree can be also used to predict many other protein attributes, such as subcellular localization, membrane protein type, enzyme functional class, GPCR type, protease type, among many others.