How does the role of chaperones differ from that of the proteasome?

Chaperones play a crucial role in aiding protein folding, which is essential for the proper functioning of proteins within the cell. They assist nascent polypeptides in acquiring their correct three-dimensional structure, thereby preventing misfolding that can lead to dysfunctional proteins. Chaperones bind temporarily to unfolded or misfolded proteins, providing an environment conducive to correct folding and sometimes even facilitating the refolding process. This action is vital for maintaining cellular homeostasis and ensuring the functional integrity of the proteome.

In contrast, the proteasome is responsible for degrading misfolded or damaged proteins that the chaperones could not assist effectively. It recognizes polyubiquitylated substrates, which typically denote proteins marked for destruction due to being dysfunctional or damaged. The proteasome is an essential component of the protein quality control system, ensuring that improperly folded or surplus proteins are broken down and recycled.

The distinction between the roles of chaperones and proteasomes highlights the symbiotic relationship within the cellular protein management system—chaperones promote proper protein formation, while proteasomes manage quality control through protein degradation.