Chaperones and chaperonins are both types of proteins that assist in the folding of other proteins. However, they differ in their structure and mechanism of action.
Chaperones, also known as heat shock proteins, are a diverse group of proteins that assist in the folding, stabilization, and degradation of other proteins. They bind to partially folded or unfolded proteins and prevent them from aggregating or being degraded, allowing the protein to fold correctly.
Chaperones can be found in various cellular compartments, including the cytoplasm, nucleus, and mitochondria. They typically function as monomers or dimers.
Chaperonins, on the other hand, are a specific class of chaperones that form large, barrel-shaped structures. They encapsulate and isolate their target protein during the folding process.
Chaperonins are typically found in the cytoplasm of prokaryotic and eukaryotic cells. They function as multi-subunit complexes. The most well-known chaperonin is GroEL/GroES (a bacterial chaperonin that consists of two stacked heptameric rings, each of which contains seven identical subunits).
The lid of the GroEL complex is formed by the GroES heptameric ring. When a protein enters the central cavity of the GroEL complex, the lid of the complex closes over the top to create an isolated folding chamber for the target protein.
Summarizing, both chaperones and chaperonins both play important roles in protein folding.
However, chaperonins are a specific type of chaperones that forms a barrel-shaped structure around their target protein.