γ-Crystallin (bovine), (native)

The crystallins are structural proteins most highly expressed in lens fiber cells of the vertebrate eye. The crystallins are divided into two subfamilies: the alpha-crystallins (alphaA and alphaB) which are members of the small heat shock protein superfamily, also functioning as molecular chaperones; and the evolutionarily-linked superfamily of beta- and gamma-crystallins which comprise the majority of soluble protein in the lens, and contribute to the transparency and refractive properties of lens structure. There are four major gamma-crystallin classes: terrestrial (gammaA-F); aquatic (fish-gammaM); gamma-S; and gamma-N, a beta-gamma-hybrid crystallin. The beta- and gamma-crystallins share structural homology in the presence of four modified Greek key beta-gamma-motifs, but differ in that monomeric gamma-crystallins lack N-terminal extensions present in beta-crystallins that promote oligomerization. Alterations in gamma-crystallin gene expression leads to aggregation of misfolded protein in the lens, and has been linked to the development of congenital cataracts in humans. The predicted molecular weight of bovine gamma-crystallin is approximately 20-21 kDa.