Origin of urea-soluble protein in the selenite cataract. Role of β-crystallin proteolysis and calpain II

L. L. David, B. M. Dickey, T. R. Shearer

Research output: Contribution to journalArticle

18 Scopus citations


Nuclear cataract resulting from an overdose of selenite was characterized by a five-fold increase in nuclear urea-soluble protein. The origin of this urea-soluble protein was examined by two-dimensional electrophoresis, immunoblotting with monospecific antisera against rat lens crystallins, and tryptic mapping. Cataractous urea-soluble protein was primarily composed of insolubilized β- and γ-crystallin polypeptides. Polypeptides from cataractous urea-soluble protein, and normal β(L)-crystallin aggregates were compared by tryptic mapping. Approximately 19% of the urea-soluble protein from opaque nuclei was composed of 24.7 and 24.0 K polypeptides derived by limited proteolysis of 26.5 K β(L)-crystallin polypeptide. Incubation of 26.5 K β-crystallin polypeptide with purified rat lens calpain II in vitro caused production of fragments with similar molecular weights to polypeptides found in cataractous lenses. These results support the hypothesis that proteolysis may contribute to formation of urea-soluble protein in selenite cataract.

Original languageEnglish (US)
Pages (from-to)1148-1156
Number of pages9
JournalInvestigative Ophthalmology and Visual Science
Issue number7
StatePublished - Jan 1 1987


ASJC Scopus subject areas

  • Ophthalmology
  • Sensory Systems
  • Cellular and Molecular Neuroscience

Cite this