Hsp70: A Multi-Tasking Chaperone at the Crossroad of Cellular Proteostasis
Molecular chaperones are key components of protein quality control machineries in all biological systems. Members of Hsp70 group of molecular chaperones are one of the most commonly found chaperones that accomplish multitude of cellular activities in concert with its co-chaperones. Hsp70s are involved in almost all aspects of protein quality control starting from de novo protein folding, prevention of misfolded or aggregated protein formation to membrane translocation and degradation of terminally misfolded proteins. Barring few exceptions, all known Hsp70s accomplish cellular activities by consuming energies from ATP-hydrolysis by their ATPase activity. The ATP-hydrolysis-driven chaperoning activities of Hsp70s are always assisted and regulated by two groups of co-chaperones; J-domain proteins (JDPs) or Hsp40s and nucleotide exchange factors (NEFs), to accomplish cellular functions in physiological time frames. As the co-chaperones especially the JDPs outnumber the Hsp70s, it is thought that different co-chaperone networks actually bestow the multi-tasking ability to particular Hsp70. In this chapter, an overview of recent understanding of various cellular activities of Hsp70s assisted by its co-chaperones have been discussed to highlight the extent of diversity of cellular functions achieved by this group of molecular chaperones.
KeywordsHeat shock proteins Hsp70 Molecular chaperones Protein folding Proteostasis
We sincerely acknowledge Dr. Kausik Chakraborty, Asmita Ghsoh and Joshua Jebakumar Peter for their critical comments on the chapter.
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