Molecular chaperones are large, proteinaceous molecules that play an important role in the correct folding of other proteins. Proper protein folding is essential for the function of many cellular proteins. In addition, correctly folded proteins are less likely to clump together and form aggregates that can be toxic to cells.
Molecular chaperones are found in all cells and are especially abundant in cells that experience a lot of protein turnover, such as cells in the immune system and the spleen. Molecular chaperones can be either client proteins or Hsp70 proteins. Client proteins are proteins that need to be folded and are assisted by Hsp70 proteins. Hsp70 proteins are themselves molecular chaperones that play an important role in the correct folding of other proteins, as well as in the unfolding and refolding of proteins that have become denatured.
Molecular chaperones are often found in complex with other proteins, such as co-chaperones. Co-chaperones help to stabilize the fold of the client protein or help with the release of the client protein from the Hsp70 protein.
Molecular chaperones play an important role in many cellular processes, including cell division, stress response, and protein degradation. In addition, molecular chaperones have been implicated in a number of diseases, including cancer, Alzheimer’s disease, and Parkinson’s disease.
Molecular chaperones caught in flagrante
A recent study has uncovered a new role for molecular chaperones in cell biology. Not only do they help proteins fold correctly, but they also play a part in ensuring the fidelity of protein-protein interactions.
Molecular chaperones are a class of proteins that help other proteins fold correctly. They do this by preventing misshapen proteins from aggregating and by assisting in the correct folding of newly synthesized proteins.
Molecular chaperones are also thought to play a role in protein quality control, by selectively degrading misfolded proteins.
Now, a study led by scientists at the University of California, San Diego, has uncovered a new role for molecular chaperones in cell biology.
The study, published in the journal Nature, shows that molecular chaperones can also help ensure the fidelity of protein-protein interactions.
Using a combination of genetic, biochemical, and biophysical techniques, the scientists showed that the molecular chaperone Hsp70 can bind to and stabilize an assembled protein complex.
Further experiments showed that Hsp70 can also ensure the proper assembly of a protein complex by preventing the binding of an incorrect subunit.
“Our study provides the first direct evidence that Hsp70 can bind to and stabilize an assembled protein complex,” said senior author Martin Krieger, a professor of pharmacology at UC San Diego School of Medicine.
“We also show that Hsp70 can help ensure the proper assembly of a protein complex by preventing the binding of an incorrect subunit.”
The findings suggest that Hsp70 and other molecular chaperones may play a more important role in cell biology than previously appreciated.
“Molecular chaperones are often thought of as ‘folding helpers,'” Krieger said. “But our study suggests that they may also be ‘quality control policemen,’ making sure that only properly assembled proteins are allowed to remain in the cell.”
