Publication Details

This article was originally published as Aquilina, A and Watt, S, The N-terminal domain of alphaB-crystallin is protected from proteolysis by bound substrate, Biochemical and Biophysical Research Communications, 353, 2007, 1115-1120. The original journal is available at http://www.elsevier.com/wps/find/journaldescription.cws_home/622790/description#description . Copyright Elsevier 2007.


alpha-Crystallin, a major structural protein of the lens can also function as a molecular chaperone by binding to unfolding substrate proteins. We have used a combination of limited proteolysis at low temperature, and mass spectrometry to identify the regions of alpha-crystallin directly involved in binding to the structurally compromised substrate, reduced alpha-lactalbumin. In the presence of trypsin, alpha-crystallin which had been pre-incubated with substrate showed markedly reduced proteolysis at the C-terminus compared with a control, indicating that the bound substrate restricted access of trypsin to R157, the main cleavage site. Chymotrypsin was able to cleave at residues in both the N- and C-terminal domains. In the presence of substrate, alpha-crystallin showed markedly reduced proteolysis at four sites in the N-terminal domain when compared with the control. Minor differences in cleavage were observed within the C-terminal domain suggesting that the N-terminal region of alpha-crystallin contains the major substrate interaction sites.



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