Document Detail


The chaperone action of bovine milk α(S1)- and α(S2)-caseins and their associated form α(S)-casein.
MedLine Citation:
PMID:  21457703     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
α(S)-Casein, the major milk protein, comprises α(S1)- and α(S2)-casein and acts as a molecular chaperone, stabilizing an array of stressed target proteins against precipitation. Here, we report that α(S)-casein acts in a similar manner to the unrelated small heat-shock proteins (sHsps) and clusterin in that it does not preserve the activity of stressed target enzymes. However, in contrast to sHsps and clusterin, α(S)-casein does not bind target proteins in a state that facilitates refolding by Hsp70. α(S)-Casein was also separated into α(S1)- and α(S2)-casein, and the chaperone abilities of each of these proteins were assessed with amorphously aggregating and fibril-forming target proteins. Under reduction stress, all α(S)-casein species exhibited similar chaperone ability, whereas under heat stress, α(S1)-casein was a poorer chaperone. Conversely, α(S2)-casein was less effective at preventing fibril formation by modified κ-casein, whereas α(S)- and α(S1)-casein were comparably potent inhibitors. In the presence of added salt and heat stress, α(S1)-, α(S2)- and α(S)-casein were all significantly less effective. We conclude that α(S1)- and α(S2)-casein stabilise each other to facilitate optimal chaperone activity of α(S)-casein. This work highlights the interdependency of casein proteins for their structural stability.
Authors:
Teresa M Treweek; David C Thorn; William E Price; John A Carver
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2011-3-29
Journal Detail:
Title:  Archives of biochemistry and biophysics     Volume:  -     ISSN:  1096-0384     ISO Abbreviation:  -     Publication Date:  2011 Mar 
Date Detail:
Created Date:  2011-4-4     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0372430     Medline TA:  Arch Biochem Biophys     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Copyright Information:
Copyright © 2011. Published by Elsevier Inc.
Affiliation:
Graduate School of Medicine, University of Wollongong, Northfields Ave, Wollongong, New South Wales, 2522, Australia.
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