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GroEL protects the sarcoplasmic reticulum Ca ‐dependent ATPase from inactivation in vitro
Author(s) -
Javed Masood Ul Hassan,
Michelangeli Francisco,
Lund Peter A.
Publication year - 1999
Publication title -
iubmb life
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.132
H-Index - 113
eISSN - 1521-6551
pISSN - 1521-6543
DOI - 10.1080/15216549900201683
Subject(s) - endoplasmic reticulum , groel , in vitro , atpase , chemistry , microbiology and biotechnology , biophysics , biology , biochemistry , enzyme , gene , escherichia coli
The molecular chaperone, GroEL, facilitates correct protein folding and inhibits protein aggregation. The function of GroEL is often, though not invariably, dependent on the cochaperone, GroES, and ATP. In this study it is shown that GroEL alone substantially reduces the inactivation of purified Ca++‐ATPase from rabbit skeletal muscle sarcoplasmic reticulum. In the absence of GroEL, the enzyme became completely inactive in about 45‐60 hours when kept at 25°C, while in the presence of an equimolar amount of GroEL, the enzyme remained approximately 80% active even after 75 hours. Equimolar amounts of BSA or lysozyme were unable to protect the enzyme from inactivation under identical conditions. Analysis by SDS‐PAGE showed GroEL was acting by blocking the aggregation of ATPase at 25°C. GroEL was not as effective in protection at ‐20°C or 4°C. These results are discussed in the context of current models of the GroEL mechanism.