Characterization of a mutant R11H αB-crystallin associated with human inherited cataract

αB-Crystallin plays an important part in cataract development. A novel mutation (R11H) was previously detected by our group. In the present study, we set out to investigate the possible molecular mechanism by which the R11H mutation causes cataract. We found that the mutant αB-crystallin exhibits folding defects, decreased surface hydrophobicity and enhanced chaperone-like activity compared with the wild-type αB-crystallin. The mutant protein shows nearly the same molecular mass and thermal stability as the wild-type form. Transfection studies revealed that the R11H mutant was remarkably similar to the wild-type protein in its subcellular distribution, but has an abnormal ability to induce cell apoptosis. These results suggest that the changes in hydrophobic exposure and the abnormal ability to induce programmed cell death of the mutant protein are likely to be responsible for the onset of cataract.