1 Introduction
DNA-binding proteins (DBPs) and RNA-binding proteins (RBPs) are two kinds of important proteins which play crucial roles in various biological processes, such as DNA replication, transcriptional control, chromatin stability and modification, epigenetic regulation, posttranscriptional gene regulation, alternative splicing, translation, etc. [1], [2], [3]. They have important functions for some diseases, such as cancer [4], myeloid leukaemia [3], [5]. Furthermore, some proteins (DRBPs) can bind to both DNA and RNA, which also play important roles in gene expression [3]. Accurate identification of DBPs, RBPs and DRBPs is significantly meaningful.