 Three prime untranslated regions ( 3'UTRs ) of messenger RNAs ( mRNAs ) often contain regulatory sequences that post @-@ transcriptionally cause RNA interference . Such 3 ' -UTRs often contain both binding sites for microRNAs ( miRNAs ) as well as for regulatory proteins . By binding to specific sites within the 3 ' -UTR , miRNAs can decrease gene expression of various mRNAs by either inhibiting translation or directly causing degradation of the transcript . The 3 ' -UTR also may have silencer regions that bind repressor proteins that inhibit the expression of a mRNA . 
