Chaperone-like activity and hydrophobicity of alpha-crystallin.
alpha-Crystallin, a prominent member of small heat shock protein (sHsp) family and a major structural protein of the eye lens is a large polydisperse oligomer of two isoforms, alphaA- and alphaB-crystallins. Numerous studies have demonstrated that alpha-crystallin functions like a molecular chaperone in preventing the aggregation of various proteins under a wide range of stress conditions. The molecular chaperone function of alpha-crystallin is thus considered to be vital in the maintenance of lens transparency and in cataract prevention. alpha-Crystallin selectively interacts with non-native proteins thereby preventing them from aggregation and helps maintain them in a folding competent state. It has been proposed and generally accepted that alpha-crystallin suppresses the aggregation of other proteins through the interaction between hydrophobic patches on its surface and exposed hydrophobic sites of partially unfolded substrate protein. However, a quantifiable relationship between hydrophobicity and chaperone-like activity remains a matter to be concerned about. On an attentive review of studies on alpha-crystallin chaperone-like activity, particularly the studies that have direct or indirect implications to hydrophobicity and chaperone-like activity, we found several instances wherein the correlation between hydrophobicity and its chaperone-like activity is paradoxical. We thus attempted to provide an overview on the role of hydrophobicity in chaperone-like activity of alpha-crystallin, the kind of evaluation done for the first time.
Reddy
G Bhanuprakash
GB
Biochemistry Division, National Institute of Nutrition, Hyderabad, India. geereddy@yahoo.com
Kumar
P Anil
PA
Kumar
M Satish
MS
D000595:Amino Acid Sequence; D000818:Animals; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D018832:Molecular Chaperones / Q000502:physiology*; D008969:Molecular Sequence Data; D020836:Protein Structure, Quaternary / Q000187:drug effects; D016415:Sequence Alignment; D038201:alpha-Crystallins / Q000737:chemistry* / Q000502:physiology*
D018832:Molecular Chaperones; D038201:alpha-Crystallins