When cell is exposed to high, non-lethal temperatures, protein http://www.cusabio.com/ aggregates form. These protein aggregates appear to be part of an organized response to stress, and not the accumulation of damaged proteins en route to destruction.
Scientists from the University of Chicago and Harvard University found that aggregates are fully reversible. After the cell returns to normal temperatures, aggregated proteins are disentangled and resume their normal cellular functions. Some proteins were found to remain intact and even functional while in an aggregated state.
Protein aggregates have been widely considered to be toxic dead-end products before. Now the findings shed new light on the biological nature of protein aggregates. Scientists increasingly recognize protein aggregates as a new layer of cellular organization.
What proteins aggregate in the cell during acute heat shock and what happens to them when the cell recovers? Surprisingly, researchers found that even the most severely aggregated proteins disassembled and went back into circulation during recovery. It raises the possibility that most of these aggregates, which before looked like damage, may actually be part of a coordinated, evolved process.
There are still many questions about how cells respond to heat shock, although scientists have done a lot of investigations. When exposed to stressful, but nonlethal temperatures, some cellular proteins aggregate into large clumps called stress granules. Studies in mutant cell line have showed that certain types of stress granules are destroyed by the cell and their protein components presumably remade. Artificially-introduced heat-sensitive proteins, as well as newly made proteins, have been shown to be aggregation-prone and destroyed by cells after heat shock. But it remained unclear that whether the vast majority of proteins in normal cells have the similar fates.
After a lot of work, more than 175 different proteins that aggregated in response to heat shock were identified. These proteins represented around a sixth of the proteins measured and about ten times as many as were known before.
Specific proteins http://www.cusabio.com/catalog-13-1.html formed granules at specific and separate cellular locations, which indicated a level of organization. However, the team also discovered that aggregation happened under many conditions where stress granules did not form. It showed that aggregation and formation of granules are related but separate processes.
