The Biology of Extracellular Molecular Chaperones

The heat shock, or cell stress, response was first identified in the polytene chromosomes of Drosophila. This was later related to the appearance of novel proteins within stressed cells, and the key signal stimulating this appearance was identified as the presence of unfolded proteins within the cell. It is now known that this is a key mechanism enabling cells to survive a multitude of physical, chemical and biological stresses. Since the promulgation of the ‘molecular chaperone’ concept as a general cellular function to control the process of correct protein folding, a large number of molecular chaperones and protein folding catalysts have been identified, and it has bee…