What are molecular chaperones and how do they assist protein folding?

Molecular chaperones are proteins that assist in the proper folding of other proteins without being part of the final structure. The Hsp70 family binds to hydrophobic regions of nascent polypeptides, preventing aggregation and allowing proper folding. Chaperonins (like GroEL/GroES in bacteria, TRiC in eukaryotes) provide isolated chambers where proteins can fold without interference. Hsp90 assists in the maturation of signaling proteins. Chaperones use ATP hydrolysis to drive conformational changes. Misfolding despite chaperone assistance can lead to diseases like Alzheimer's and Parkinson's.