Molecular chaperones are proteins that assist the conformational folding or unfolding and the assembly or disassembly of other macromolecular structures.
Molecular chaperones are diverse families of multidomain proteins that have evolved to assist nascent proteins to reach their native fold, protect subunits from heat shock during the assembly of complexes, prevent protein aggregation or mediate targeted unfolding and disassembly.
Protein quality control, also known as proteostasis, constitutes the regulation of protein synthesis, folding, unfolding and turnover. It is mediated by chaperone and protease systems, together with cellular clearance mechanisms such as autophagy and lysosomal degradation.
The main principle of acting of chaperones is lowering energy needed for folding protein. Chaperonines isolate polypeptide from the surrounding cytoplasm (hydrogen bonding with water, which requires additional energy). Chaperones doesn`t allow to misfold by bonding to hydropobic sites of peptide.