Heat Shock Proteins

High temperature (HT) is one of the major environmental stresses that affect plant growth, metabolism, and productivity. HT stress usually causes protein dysfunction. Therefore, maintaining proteins in their functional conformations and preventing the aggregation of non-native proteins are particularly important for cell survival under stress. Plants have evolved a wide array of mechanisms for adaption to stressful environments such as induction of heat shock proteins (HSPs). According to molecular weight HSPs are of various types such as HSP100, HSP90, HSP70, HSP60, and small heat shock proteins (sHSP). All of the major HSPs have related functions of ameliorating the problems caused by protein misfolding and aggregation. However, each major HSP family has a unique mechanism of action. Some promote the degradation of misfolded proteins (Lon, ubiquitin, and various ubiquitin-conjugating enzymes), whereas others bind to different types of folding intermediates and prevent them from aggregating (HSP70 and HSP60) and promotes the reactivation (HSP100) of proteins that have already aggregated. These are responsible for protein folding, assembly, translocation, reestablishing normal protein conformation, and can assist in protein refolding under stress conditions.