Chaperones are specialized proteins that play a crucial role in assisting the folding of other proteins in the cell. They help in the correct folding of proteins by preventing misfolding, aggregation, and promoting the proper folding of nascent polypeptides. Chaperones can be classified into two main categories: molecular chaperones and chaperonins.1. Molecular chaperones: These proteins bind to nascent or unfolded polypeptides and prevent their aggregation during the folding process. They do not actively participate in the folding process but provide a suitable environment for the protein to fold correctly. Some common molecular chaperones include heat shock proteins HSPs such as Hsp70 and Hsp90.The mechanism of action of molecular chaperones involves the following steps:a. Recognition: Molecular chaperones recognize and bind to hydrophobic regions of the unfolded or partially folded protein. This binding prevents the exposed hydrophobic regions from interacting with other proteins, thus preventing aggregation.b. Stabilization: By binding to the unfolded protein, molecular chaperones stabilize the intermediate folding states, allowing the protein to fold correctly.c. Release: Once the protein has achieved its correct folded conformation, the chaperone releases the protein, which can now perform its biological function.2. Chaperonins: These are large, multisubunit protein complexes that provide a protected environment for protein folding. They actively participate in the folding process by using energy derived from ATP hydrolysis. The two main types of chaperonins are Group I chaperonins, such as GroEL/GroES in bacteria, and Group II chaperonins, such as TRiC/CCT in eukaryotes.The mechanism of action of chaperonins involves the following steps:a. Encapsulation: The unfolded protein binds to the chaperonin complex, which then encapsulates the protein within a central cavity.b. Folding: The chaperonin complex provides a protected environment for the protein to fold correctly. The energy derived from ATP hydrolysis drives conformational changes in the chaperonin complex, which in turn facilitates the folding of the encapsulated protein.c. Release: Once the protein has achieved its correct folded conformation, the chaperonin complex releases the protein, which can now perform its biological function.In summary, chaperones play a critical role in protein folding by preventing aggregation, stabilizing intermediate folding states, and promoting the correct folding of proteins. They ensure that proteins achieve their proper conformation and maintain cellular homeostasis.