Eye-lens proteins: structure, superstructure, stability, genetics.

The eye lens in vertebrates and invertebrates is an avascular tissue which allows one to focus objects on the retina. The lens grows throughout life, maintaining transparency without significant turnover of its densely packed proteins. Apart from cytoskeletal and taxon-specific components, these proteins belong mainly to the alpha- and beta gamma-crystallin families. The detailed structural analysis of beta gamma-crystallins can explain the anomalous stability by the specific supersecondary structure ("Greek key" topology) of the domains and by strong domain and subunit interactions. The spatial correlation of the molecules at the given high concentrations in the fiber cells gives rise to "short-range order" with minimum light scattering, thus providing optimum transparency of the eye lens.