Gamma-B crystallin (eye lens components protein)
Bos taurus (Bovine)
Crystallins are a family of proteins that form the dominant structural components of the eye lens in vertebrates. The three major classes of crystallins are alpha, beta and gamma. Beta and gamma-crystallins are structural proteins while the alpha-crystallins are molecular chaperones (proteins that prevent and protect other proteins from aggregating or misfolding) and structural proteins. However, crystallins have also been found outside the eye. The eye lens fibre cells are packed with crystallins that account for the transparency of the lens and produce the correct refractive index and minimal light scattering. Crystallins are expressed in the early stages of development and they have minimal turnover (degradation and reexpression). Hence they are required to be highly stable. Aggregation or crystallization of crystallins, or their loss of solubility or stability, results in the loss of their function causing cataracts.
The structure shown here is that of gamma-B crystallin from the bovine eye lens. gamma-crystallins (along with beta-crystallins) form a family of closely related proteins comprised of 2 domains rich in beta sheets. The beta sheets in each domain are folded into 2 similar Greek key motifs. gamma-crystallins are always found as monomers and their mutations are believed to be responsible for the development of cataracts.
Protein Data Bank (PDB)
Najmudin, S. Nalini, V. Driessen, H.P.C. Slingsby, C. Blundell, T.L. Moss, D.S. Lindley, P.F.; "STRUCTURE OF THE BOVINE EYE LENS PROTEIN GAMMA-B(GAMMA-II)-CRYSTALLIN AT 1.47 ANGSTROM."; Acta Crystallogr.; (1993) D49:223-233 PubMed:15299528.
author: Ashwini Patil