The importance of protein-RNA interactions has been demonstrated in both eukaryotes and prokaryotes.For example, piRNAs, a class of about 30-nt small RNAs isolated from mammalian germ cells, play their regulatory roles through interacting with the proteins from PIWI family.In addition, the interaction CsrA-CsrB in E.coli can regulate glycogen catabolism, in which CsrB is a small regulatory RNA (sRNA) of 360 nucleotides in length, and CsrA is an RNA-binding protein of 61-amino-acid.The CsrA can repress glycogen synthesis by binding to and destabilizing glgCAP or other mRNAs.