Identification of a 9 kDa γ-crystallin fragment in human lenses

Age-related Changes in Human Lens Crystallins Identified by Two-dimensional Electrophoresis and Mass Spectrometry

“…While extensively degraded crystallins, such as a 9 kDa form of γD (Srivastava, McEntire and Srivastava, 1992) and 9n6 kDa form of αA (Roy and Spector, 1978) have been reported in human lens, other than the loss of βB1 and βA3 N-terminal extensions, the present studies detected no other fragmented crystallins in the water-soluble fraction. Extensively degraded crystallins were not detected in the present study because the 12 % polyacrylamide gels used only resolved proteins larger than approximately 14 kDa.…”

Deamidation and Disulfide Bonding in Human Lens γ-Crystallins

“…A minor product showing a loss of the C-terminal Glu of γS-crystallin was the only degradation detected. The previously reported 8 kDa fragment of γS-crystallin (Srivastava et al, 1993) and the 9 kDa fragment of γD-crystallin (Srivastava et al, 1992 ;Srivastava and Srivastava, 1996) were not observed, probably because they are present in very low amounts and co-eluted with the unmodified form in reversed phase HPLC separations. A modified γ-crystallin present at less than 5 % of the total protein in a fraction, may not be detected in the mass spectrum.…”

“…An 8 kDa fragment of γS-crystallin (Srivastava, Srivastava and Silney, 1993) and a 9 kDa fragment of γD-crystallin (Srivastava, McEntire and Srivastava, 1992) were identified by their amino acid sequences following separation by SDS-PAGE. The 8 kDa molecular weight of the γS-crystallin fragment did not agree with the proposed cleavage site.…”

Characterization of Low Molecular Mass γ-Crystallin Fragments from Human Lenses

“…As the lens ages, this stability decreases and low molecular mass fragments of 10-14 kDa, derived from γ-crystallins, appear as minor constituents of both the water-soluble and insoluble proteins of the lens (Takemoto, Straatsma and Horwitz, 1989 ;Srivastava, McEntire and Srivastava, 1992 ;Srivastava, Srivastava and Silney, 1993 ;Srivastava, Srivastava and Silney, 1994 ;Srivastava and Srivastava, 1996 ;Srivastava, 1988). Because the abundance of degraded polypeptides of γ-crystallins increases with age and these degraded proteins may be intermediates in the development of cataract, there is particular interest in identifying the low molecular mass fragments of γ-crystallins.…”