Protein folding is done by -

Ans. is 'a' i.e., Chaperones o Certain proteins play a role in the assembly or proper folding of other proteins without themselves being components of the lattero Such proteins are called molecular chaperones,o Most chaperones exhibit ATPase activity and bind ADP and ATP.o This activity is important for their effect on folding.Some Properties of Chaperone Proteinso Present in a wide range of species from bacteria to humanso Many are so-called heat shock proteins (Hsp)o Some are inducible by conditions that cause unfolding of newly synthesized proteins (eg, elevated temperature and various chemicals)o They blind to predominantly hydrophobic regions of infolded proteins and prevent their aggregationo They act in part as a quality control or editing mechanism for detecting misfolded or otherwise defective proteinso Most chapersones show associated ATPase activity, with ATP or ADP being involved in the protein-chaperone interactiono Found in various cellular compartments such as cytosol, mitochondria, and the lumen of the endoplasmic reticulumSome Chaperones and Enzymes involved in Folding That Are Located in the Rough Endoplasmic Reticulumo BiP (immunoglobulin heavy chain binding protein)o GRP94 (glucose-regulated protein)o Calnexino Calreticulino PDI (protein disulfide isomerase)o PPI (peptidyl proly cis-trans isomerase)