mRNA 3 ′ end processing and more-multiple functions of mammalian cleavage factor I-68

The formation of defined 3 ′ ends is an important step in the biogenesis of mRNAs. In eukaryotic cells, all mRNA 3 ′ ends are generated by endonucleolytic cleavage of primary transcripts in reactions that are essentially posttranscriptional. Nevertheless, 3 ′ end formation is tightly connected to transcription in vivo, and a link with mRNA export to the cytoplasm has been postulated. Here, we briefly review the current knowledge about the two types of mRNA 3 ′ end processing reactions, cleavage/polyadenylation and histone RNA processing. We then focus on factors shared between these two reactions. In particular, we discuss evidence for new functions of the mammalian cleavage factor I subunit CF I m68 in histone RNA 3 ′ processing and in the export of mature mRNAs from the nucleus to the cytoplasm. © 2010 John Wiley & Sons, Inc.