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

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Abstract

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
Volume28
Issue number7
StatePublished - 1987

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Selenious Acid
Crystallins
Calpain
Cataract
Proteolysis
Urea
Peptides
Lenses
Proteins
Immunoblotting
Electrophoresis
Immune Sera
Molecular Weight

ASJC Scopus subject areas

  • Ophthalmology

Cite this

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title = "Origin of urea-soluble protein in the selenite cataract. Role of β-crystallin proteolysis and calpain II",
abstract = "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.",
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year = "1987",
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T1 - Origin of urea-soluble protein in the selenite cataract. Role of β-crystallin proteolysis and calpain II

AU - David, Larry

AU - Dickey, B. M.

AU - Shearer, Thomas (Tom)

PY - 1987

Y1 - 1987

N2 - 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.

AB - 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.

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