Hierarchy of lens proteins requiring protection against heat-induced precipitation by the α crystallin chaperone

Pauline T. Velasco, Thomas J. Lukas, S. N. Prasanna Murthy, Yvonne Duglas-Tabor, Donita L. Garland, Laszlo Lorand*

*Corresponding author for this work

Research output: Contribution to journalArticle

21 Scopus citations

Abstract

Gel filtration of the water-soluble extract from bovine lens yields a group of proteins, emerging between the peaks of β(H) and β(L) crystallins, which show a considerably greater sensitivity to heat-induced aggregation/precipitation than the far more abundant β and γ crystallins. However, the small heat shock protein: α crystallin was effective in protecting these trace constituents of the lens from precipitating out of solution at 55 °C (measured under the standard conditions in a pH 7.5 buffer containing 50 mM sodium phosphate, 100 mM NaCl, 1 mM EDTA and 0.05% NaN3). Prominent components of the precipitate, formed in the absence of a recombinant αB crystallin chaperone could be resolved by one- and two- dimensional electrophoresis. Identification by amino acid sequencing revealed that the heat-sensitive group of lens proteins comprised glyceraldehyde-3- phosphate dehydrogenase (M(r) ~ 39 kDa), enolase (~ 48 kDa), leucine aminopeptidase (~ 52 kDa) and aldehyde dehydrogenase (~ 53 kDa). These findings indicate for the first time that the aggregation of such minor lens constituents could possibly contribute to initiating the process of opacification in the development of cataracts.

Original languageEnglish (US)
Pages (from-to)497-505
Number of pages9
JournalExperimental eye research
Volume65
Issue number4
DOIs
StatePublished - Oct 1997

Keywords

  • Cataract
  • Chaperone
  • Lens enzymes
  • Thermal aggregation
  • α crystallin

ASJC Scopus subject areas

  • Ophthalmology
  • Sensory Systems
  • Cellular and Molecular Neuroscience

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