Sequence analysis of lens β-crystallins suggests involvement of calpain in cataract formation

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Abstract

Abnormal activation of the protease calpain in the lens may be a cause of cataracts. Cataracts were induced in 10-day-old rats by a single overdose of sodium selenite. The water-insoluble protein from the opaque lens nucleus was separated by two-dimensional electrophoresis, electroblotted onto membranes, and the NH2-terminal sequence of partially degraded β-crystallin polypeptides determined. Selenite cataractous lenses contained four major structural proteins, βB1, βB3, βA3/A1, and βA4 crystallins, missing from 5 to 49 amino acids from their NH2 termini. Incubation of intact β- crystallins with calpain II in vitro produced identical cleavage sites. This provided further evidence for the role of calpain in the production of light scattering insoluble protein in cataractous lenses and also suggested that a similar process may lead to lens protein insolubilization during aging.

Original languageEnglish (US)
Pages (from-to)1937-1940
Number of pages4
JournalJournal of Biological Chemistry
Volume268
Issue number3
StatePublished - Jan 1 1993

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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