Enzyme/crystallins: Gene sharing as an evolutionary strategy

Crystallins fall into two categories: the ubiquitous crystallins, represented in all vertebrate lenses ( alpha , beta , and gamma ), and those present only in certain species, the taxon-specific crystallins. Despite the apparent ability of the the transparent lens to tolerate a large variety of proteins and still perform its specialized function, each crystallin has been highly conserved in evolution. The ubiquitous crystallins also show unusually high conservation of surface charges. A possible solution to the paradox that crystallins are highly conserved in sequence while extremely diverse in number and distribution is the unexpected fact that many crystallins have vital functions outside the lens.