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K. L. Schey, Z. Ablonczy, Y. Berry, R. J. W. Truscott; Quantitative Proteomics of Human Lens Barrier Membrane Proteins. Invest. Ophthalmol. Vis. Sci. 2007;48(13):4423.
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© ARVO (1962-2015); The Authors (2016-present)
To determine membrane protein changes in the barrier region of human lenses using quantitative proteomics. The onset of the barrier at middle age is thought to be the key event that predisposes lenses to age-related nuclear cataract.
The barrier region from young (19-23y) and old (75-77y) human lenses was dissected, homogenized, and washed with urea prior to centrifugation to produce a membrane fraction. Proteins from four samples (two young and two old lenses) were digested with trypsin and labeled with iTRAQ reagents followed by two dimensional HPLC and tandem mass spectrometry. iTRAQ reporter ion intensities were used to quantitate protein expression differences between samples and Mascot and ProQuant search algorithms were used for protein identification.
Up to 90 proteins were identified in the human lens barrier regions. Significant differences in protein expression between old and young regions were observed. For example, cytoskeletal proteins were decreased in abundance in the older lens barrier membrane fraction and specific crystallins (γC, γD, γS, ßB1 and ßA4) were increased in older lens barrier regions.
Quantitative proteomics revealed significant changes in protein abundance in the membrane fraction isolated from the lens barrier region of old and young human lenses. Redistribution of cytoskeletal proteins, in general, and of specific crystallin proteins occurs at the fiber cell plasma membrane as the lens barrier forms in older lenses.
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