The nontranslating RNA molecules leads to the formation of granular structures like Stress granules and P-bodies. They are specialized strucutures. How these are interrelated with each other. In which pathway they are linked.
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Thank you Niran Maharjan daju, I have watched this wonderful video by Parker which also helped me in powerpoint preparation. Still, there is no clear correlation between P-bodies and Stress Granules and their interchange.
Eukaryotic cells contain multiple cytoplasmic RNA–protein complexes referred to as RNP granules, such as P-bodies and stress granules. P-bodies, which are generally seen in all cell types, contain mRNA decay proteins, whereas stress granules form during cellular stress (such as UV irradiation, heat shock, oxidative stress) and contain numerous translation initiation factors, including small ribosomal subunits.
P-bodies (Processing bodies) are complexes of translationally repressed mRNAs associated with a large number of proteins involved in translation repression, RNA interference, mRNA surveillance and mRNA degradation. Translation initiation factors and ribosomal proteins are generally excluded from P-bodies with the exception of eIF4E in mammalian P-bodies. P-bodies are dynamic complexes whose assembly is dependent on, and proportional to, the pool of nontranslating mRNA.
Like P-bodies, stress granules are dynamic and reversible complexes whose assembly is dependent on the pool of nontranslating mRNAs. Although they share some components in common with P-bodies, stress granules typically contain translation initiation factors eIF4E, eIF4G, eIF4A, eIF4B, poly-A binding protein, eIF3, eIF2, and the 40S ribosomal subunit. Stress granules were fi rst observed under stress conditions, in which translation initiation is often inhibited. However, it is now clear that stress granule formation is not limited to stress conditions, but can occur in response to a variety of blocks in translation initiation. For example, inhibition of translation initiation using drugs, knock-down of translation initiation factors, or over-expression of translation repressors have all been shown to induce stress granules.
Both types of particle can coexist in one cell, and the size and numbers of both increase under stress conditions. mRNAs may be exchanged between the two types of particle. In the presence of polysome stabilizing drugs, which trap mRNAs in a static state of translation, both P-bodies and stress granules become smaller or disappear, suggesting that the granule mRNAs are normally in a dynamic equilibrium with the population of mRNAs being translated.
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