Srinivas 6 α - Crystallins , small heat shock proteins with diverse functions in cell survival and stress tolerance

α-Crystallin, a multimeric protein, composed of αAand αB-crystallin subunits is abundantly present in the eye lens. Both the crystallin subunits have also been found in other tissues and exhibit sequence homology with small heat shock proteins. The expression of αB-crystallin is induced under heat and other stresses and in several neurodegenerative diseases. As a member of the small heat shock protein family, it confers thermo-tolerance to cells, exhibits molecular chaperone activity in preventing aggregation of proteins, prevents amyloid fibril formation, prevents Correspondence/Reprint request: Dr. Ch. Mohan Rao, Deputy Director (Director Grade Scientist), Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad 500007, India. E-mail: [email protected] Ch. Mohan Rao et al. 94 thermal inactivation of enzymes and helps in refolding enzymes either alone or with the help of other heat shock proteins. Growing evidences show that it also involved in important cellular events such as cell differentiation, apoptosis, protein turn over and quality control indicating that α-crystallin plays a diverse functional role. Its involvement in several neurodegenerative diseases and cancer suggests that a complete understanding of its role may mark this small heat shock protein a potential therapeutic target.