Unusual Degradation Pathway For Ribosomes Discovered
Ribosomes are the cell’s translation engines. They use genetic information to build chains of amino-acids that afterwards fold to form proteins. The construction of ribosomes in the cell nucleus and the translation work they perform are among the cell’s most energy-intensive processes. During periods of energy shortage the cell needs to save energy and materials and must be able to adapt rapidly to changing environmental conditions. This means that the ribosomes must be taken out of circulation as quickly as possible to halt the translation and protein building. This makes amino-acids available to the cell as components of the proteins needed to maintain homeostasis, i.e. the cell’s equilibrium.
ETH Zurich researchers from the Institute of Biochemistry have discovered a new metabolic pathway used by starving yeast cells to dispose of ribosomes very quickly and selectively. The cells do this by using a novel autophagy process which the biochemists have named “ribophagy”.
In ribophagy 1. the ribosome’s two sub-units are first of all separated. 2. The larger of the two, sub-unit S60, is labelled for selective degradation by an enzyme, a protease, cleaving a molecule of ubiquitin from the ribosome or from a protein that interacts with it. 3. A transport vesicle ingests the S60 and carries it to the cell vacuole, where numerous enzymes dismantle the sub-unit into its individual components.
NEW INSIGHTS
1. Fact that the cell uses ubiquitin as a label and/or regulator for an autophagy process.
2. Mono-ubiquitination had never before been found as a ‘labelling’ in an autophagy process.
This essential finding in Nature Cell Biology interlinks autophagy (self destruction of organelles) and proteosome activity (protein degradation)
Ribophagy is another piece in the jigsaw towards a better understanding of diseases such as Alzheimer’s or Parkinson’s.
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Mitosis Gets Harder Thanks To New Gene Discovery
ETH Zurich researchers from the Institute of Biochemistry have discovered a new metabolic pathway used by starving yeast cells to dispose of ribosomes very quickly and selectively. The cells do this by using a novel autophagy process which the biochemists have named “ribophagy”.
In ribophagy 1. the ribosome’s two sub-units are first of all separated. 2. The larger of the two, sub-unit S60, is labelled for selective degradation by an enzyme, a protease, cleaving a molecule of ubiquitin from the ribosome or from a protein that interacts with it. 3. A transport vesicle ingests the S60 and carries it to the cell vacuole, where numerous enzymes dismantle the sub-unit into its individual components.
NEW INSIGHTS
1. Fact that the cell uses ubiquitin as a label and/or regulator for an autophagy process.
2. Mono-ubiquitination had never before been found as a ‘labelling’ in an autophagy process.
This essential finding in Nature Cell Biology interlinks autophagy (self destruction of organelles) and proteosome activity (protein degradation)
Ribophagy is another piece in the jigsaw towards a better understanding of diseases such as Alzheimer’s or Parkinson’s.
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Mitosis Gets Harder Thanks To New Gene Discovery
Biological process taught to every student studying biology has just become a little more complicated thanks to a new discovery. Scientists from the University of Bath have found that a protein called RASSF7 is essential for mitosis, the process by which a cell divides in two.
As being one of Nature’s most important processes, interest in mitosis stems from the fact that if you want to kill cancer cells, then stopping them from dividing is a useful way of doing this.
During mitosis, the chromosomes containing the DNA are pulled apart in two halves by an array of microtubules centred on the centrosomes. Without the RASSF7 protein, the microtubules do not develop properly and cell division is halted.
Several cancer treatments block cell division by targeting microtubules, Taxol is a well known example. It is even possible that RASSF7 might be a future drug target.
As being one of Nature’s most important processes, interest in mitosis stems from the fact that if you want to kill cancer cells, then stopping them from dividing is a useful way of doing this.
During mitosis, the chromosomes containing the DNA are pulled apart in two halves by an array of microtubules centred on the centrosomes. Without the RASSF7 protein, the microtubules do not develop properly and cell division is halted.
Several cancer treatments block cell division by targeting microtubules, Taxol is a well known example. It is even possible that RASSF7 might be a future drug target.
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