How to translate text using browser tools
29 December 2008 Evolution of Mollusc Lens Crystallins: Glutathione S-transferase/S-crystallins and Aldehyde Dehydrogenase/Ω-crystallins
Joram Piatigorsky
Author Affiliations +

Diverse crystallins (abundant water-soluble proteins) are responsible for the optical properties of transparent cellular eye lenses and are multifunctional proteins that have been recruited from stress proteins and enzymes by enhanced lens expression. The major (S-crystallins) and minor (Ω-crystallin) cephalopod crystallins were recruited from glutathione S-transferase (GST) and aldehyde dehydrogenase (ALDH), respectively. S-crystallins underwent multiple gene duplications while Ω-crystallin appears to be encoded in a single-copy gene. Except for one S-crystallin (considered a “molecular fossil”), S-crystallins lack enzyme activity due to mutation and insertion of a variable central peptide by exon shuffling. The Ω-crystallin is the sole crystallin in scallops. Scallop Ω-crystallin does not bind the co-factor NAD /NADH, lacks enzyme activity, and is a tetramer but migrates as a dimer by gel filtration, suggesting structural adaptations for crystallin function. Similar transcription factors (Pax6 among others) appear to drive high lens expression of crystallin genes in molluscs and other species consistent with convergent recruitment of the non-homologous crystallin genes.

Joram Piatigorsky "Evolution of Mollusc Lens Crystallins: Glutathione S-transferase/S-crystallins and Aldehyde Dehydrogenase/Ω-crystallins," American Malacological Bulletin 26(1/2), 73-81, (29 December 2008).
Received: 11 September 2007; Accepted: 29 July 2008; Published: 29 December 2008
gene expression
lens proteins
Get copyright permission
Back to Top