Investigating the Origin of Aggregates
Aggregates of unwanted proteins are important in aging, and researchers continue to investigate why it is that aggregates appear in the first place. Here, researchers "have solved a long-standing mystery of how cells conduct 'quality control' to eliminate the toxic effects of a certain kind of error in protein production. ... The new study suggests how cells in eukaryotic organisms, like humans, sense and destroy 'non-stop' proteins that remain stuck in the ribosome, the protein manufacturing plant of the cell. ... DNA is used to make RNA, which, in turn, is used to make proteins. In healthy cells, the ribosome translates the code carried by a messenger RNA (mRNA) to link together protein building blocks (amino acids) in a particular order to form specific proteins. But errors happen - which is why the body has a host of different quality control mechanisms to ensure that the proteins that emerge from this process are flawless. When aberrant proteins escape these surveillance mechanisms, they accumulate and form 'aggregates' that can be toxic to certain neuronal types, and disorders such as Alzheimer's and Parkinson's diseases can result. ... For some 15 years, scientists have understood the mechanism that identifies and destroys these problematic non-stop proteins in bacteria. In these organisms, non-stop proteins are tagged by a marker known as tmRNA or ssrA, which then leads to their destruction. In more complex eukaryotic organisms, which range from yeast to humans, though, the mechanism for identifying and eliminating such dangerous non-stop errors has remained a mystery - until now."
Link: http://www.eurekalert.org/pub_releases/2010-09/sri-srs090910.php