The role of macromolecular crowding in the evolution of lens crystallins with high molecular refractive index.

ABSTRACT: Crystallins are present in the lens at extremely high concentrations in order to provide transparency and generate a high refractive power of the lens. The crystallin families prevalent in the highest density lens tissues are γ-crystallins in vertebrates and S-crystallins in cephalopods. As shown elsewhere, in parallel evolution, both have evolved molecular refractive index increments 5-10% above those of most proteins. Although this is a small increase, it is statistically very significant and can be achieved only by very unusual amino acid compositions. In contrast, such a molecular adaptation to aid in the refractive function of the lens did not occur in crystallins that are preferentially located in lower density lens tissues, such as vertebrate α-crystallin and taxon-specific crystall

SUBMITTER: Zhao H 

PROVIDER: S-EPMC3151160 | biostudies-literature | 2011 Aug

REPOSITORIES: biostudies-literature