Nucleasome is a macromolecular complex that degrades mRNAs into nucleotides. Like Proteasome it exhibits a barrel-like architecture that appears to have evolved to restrict substrate access and prevent indiscriminate degradation.
Contents
Formerly this macromolecule is designated as "exosome". Particularly, because exosome is also defined as "a vesicle excreted by mammalian cells" - Exosome (vesicle), and the similar barrel-like structure that degrade proteins is named proteasome, it is reasonable to name the "nucleotide chain degrading machine" nucleasome.
Discovery
The nucleasome was discovered in 1997 by Mitchell et al.
Function
In July 2007 S. Vanacova & R. Stefl showed in an article in EMBO reports that the nucleasome acts as quality controller in the nucleus. These machines recognize and degrade not only RNA trimmings, but also incorrectly processed RNAs that contain defects.