Identification of RNA-binding proteins(RBPs)is a prerequisite for understanding the posttranscriptional gene regulation networks.However,current large-scale RBP identification strategies are mostly based on the capture of polyadenylated RNAs along with their binding proteins,leaving RBPs on non-poly(A)RNAs,including most noncoding RNAs(ncRNAs)and pre-mRNAs,largely undiscovered.