© 2005 The Japanese Biochemical Society.
Regular Paper |
Cooperation of ER-60 and BiP in the Oxidative Refolding of Denatured Proteins In Vitro
Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Gokasho, Uji, Kyoto 611-0011
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ER-60 is a PDI family protein that has protein thiol-disulfide oxidoreductase activity. It has been shown to associate with BiP in the endoplasmic reticulum. Here, we analyzed the cooperation of ER-60 and BiP in the oxidative refolding of denatured proteins in vitro. ER-60 facilitated the refolding of 20 or 30% of denatured
-lactalbumin or ribonuclease B during incubation for 80 min, and these levels of nearly doubled on the addition of BiP to the reaction mixture. BiP alone could not refold denatured ribonuclease B, but could refold denatured
-lactalbumin a little. Enhancement of oxidative refolding of
-lactalbumin by ER-60 could be detected only when ER-60 was present from the start of refolding. On surface plasmon resonance analysis, ER-60 was shown to associate with BiP. The association was not influenced by ATP or ADP. Domains a and/or b' of ER-60 were implicated in the association with BiP.