HEAT SHOCK PROTEINS – ? THE GRAND PERCEPTION ? Heat shock proteins: Heat shock proteins (Hsps) comprise a group of ubiquitous polypeptides whose expression is induced when cells are subjected to stressful conditions such as ? increasing temperature, high pressure, or toxic compounds. The induction of Hsp correlates with the abundance of unfold polypeptide chains, which suggest a protective physiological role of the proteins. Important role of Hsps: The Hsp functions as a Chaperone by either facilitating the protein back to its proper confirmation or if the damage is irreparable,then the protein is targeted for destruction. Hsp involved in the assembly and disassembly of multimeric protein structures, the translocation of proteins across membranes, and the secretion & degradation of proteins. The use of cognate heat shock protein 70 ? peptide complex to elicite an immune response against cancer and viral, bacterial and other infectious breathslim agents. Heat shock proteins don’t get denature, because of their; Better hydrogen bonds Better hydrophobic internal packing. Enhanced secondary structure. Helix dipole stabilization. Based on molecular weight, size, structure and function, the Hsp’s are classified as…. Hsp100; Hsp90; Hsp70; Hsp60 (Chaperonin); Hsp 27; etc. The molecular evolution of the small heat-shock proteins in plants:- The small Hsp have undergone a tremendous diversification in plants; whereas only a single small Hsp is found in fungi and many animals, over 20 different small Hsp’s are found in higher plants. The small Hsp in plants have diversified in both sequence & cellular localization and are encoded by at least five gene families. Recent studies shows,there are 44 small Hsp DNA and amino acid sequences were examined,using both phylogenetic analysis and analysis of nucleotide substitution patterns to elucidate the evolutionary history of the small Hsp’s.