Re-capping the message

Trends Biochem Sci. 2009 Sep;34(9):435-42. doi: 10.1016/j.tibs.2009.05.003. Epub 2009 Sep 2.


The 5'-cap structure that typifies all polymerase II-transcribed RNAs plays important roles in pre-mRNA processing and mRNA export, translation and quality control. Removal of the cap is a regulated process that is considered to be the first irreversible step in mRNA decay. An emerging view challenges this idea: mRNAs have been identified in mammalian cells that lack sequences from their 5' ends but nevertheless appear to be modified with a cap or cap-like structure. Furthermore, a cytoplasmic form of capping enzyme was recently identified that, together with a novel kinase, generates capped ends from cleaved RNAs. These and other findings provide evidence for re-capping and its possible functions.

Publication types

  • Research Support, N.I.H., Extramural
  • Review

MeSH terms

  • Animals
  • Humans
  • RNA Cap-Binding Proteins / physiology*
  • RNA Caps / chemistry
  • RNA Caps / physiology*
  • RNA Stability
  • RNA, Untranslated
  • Ribonucleoproteins / metabolism


  • RNA Cap-Binding Proteins
  • RNA Caps
  • RNA, Untranslated
  • Ribonucleoproteins