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Crystallins

  1. Wilfried W de Jong,
  2. Nicolette H Lubsen

Published Online: 15 MAR 2011

DOI: 10.1002/9780470015902.a0005906.pub2

eLS

eLS

How to Cite

de Jong, W. W. and Lubsen, N. H. 2011. Crystallins. eLS. .

Author Information

  1. Radboud University Nijmegen, Nijmegen, The Netherlands

Publication History

  1. Published Online: 15 MAR 2011

Abstract

‘Crystallins’ are defined as the abundant water soluble proteins of the eye lens. The α-, β- and γ-crystallins are found in all vertebrate lenses, including those of the lamprey, and must have been recruited as lens proteins in the ancestral vertebrate. The two α-crystallins are members of the small heat-shock protein family. The six β-crystallins and the eight (depending on species) γ-crystallins are closely related in structure and probably evolved by gene duplication and fusion from a common ancestor. Expression of the ubiquitous crystallins is limited to the lens, with the exception of αB-crystallin, which abounds in brain and muscle and is stress inducible. Additional and unrelated types of crystallins are phylogenetically restricted. These crystallins are identical to housekeeping proteins and usually encoded by the same genes.

Key Concepts:

  • Lens proteins must last the lifetime of the organism and must be highly stable.

  • The β- and γ-crystallin gene families originated in the ancestral vertebrate.

  • The exact protein composition of a lens determines the optical properties and changes with an organism's habitat.

Keywords:

  • crystallins;
  • eye lens;
  • small heat-shock proteins;
  • cataract;
  • chaperones