P-bodies

In cellular biology, P-bodies, or processing bodies, are distinct foci formed by phase separation within the cytoplasm of a eukaryotic cell consisting of many enzymes involved in mRNA turnover. P-bodies are highly conserved structures and have been observed in somatic cells originating from vertebrates and invertebrates, plants and yeast. To date, P-bodies have been demonstrated to play fundamental roles in general mRNA decay, nonsense-mediated mRNA decay, adenylate-uridylate-rich element mediated mRNA decay, and microRNA (miRNA) induced mRNA silencing. Not all mRNAs which enter P-bodies are degraded, as it has been demonstrated that some mRNAs can exit P-bodies and re-initiate translation. Purification and sequencing of the mRNA from purified processing bodies showed that these mRNAs are largely translationally repressed upstream of translation initiation and are protected from 5' mRNA decay.

P-bodies were originally proposed to be the sites of mRNA degradation in the cell and involved in decapping and digestion of mRNAs earmarked for destruction. Later work called this into question suggesting P bodies store mRNA until needed for translation.

In neurons, P-bodies are moved by motor proteins in response to stimulation. This is likely tied to local translation in dendrites.