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Modulation of H + ,K + ‐ATPase activity by the molecular chaperone ERp57 highly expressed in gastric parietal cells
Author(s) -
Fujii Takuto,
Awaka Shun-ya,
Takahashi Yuji,
Fujita Kyosuke,
Tsuji Hiroshi,
Shimizu Takahiro,
Gomi Tomoharu,
Tsukada Kazuhiro,
Sakai Hideki
Publication year - 2013
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/j.febslet.2013.10.030
Subject(s) - atpase , parietal cell , chemistry , microbiology and biotechnology , gene knockdown , enzyme , biochemistry , h(+) k(+) exchanging atpase , chaperone (clinical) , biology , secretion , gene , gastric acid , medicine , pathology
ERp57 is a ubiquitous ER chaperone that has disulfide isomerase activity. Here, we found that both ERp57 and gastric H + ,K + ‐ATPase are expressed in a sample derived from the apical canalicular membranes of parietal cells. Overexpression of ERp57 in HEK293 cells stably expressing H + ,K + ‐ATPase significantly increased the ATPase activity without changing the expression level of H + ,K + ‐ATPase. Interestingly, overexpression of a catalytically inactive mutant of ERp57 (C57S/C60S/C406S/C409S) in the cells also increased H + ,K + ‐ATPase activity. In contrast, knockdown of endogenous ERp57 in H + ,K + ‐ATPase‐expressing cells significantly decreased ATPase activity without changing the expression level of H + ,K + ‐ATPase. Overexpression and knockdown of ERp57 had no significant effect on the expression and function of Na + ,K + ‐ATPase. These results suggest that ERp57 positively regulates H + ,K + ‐ATPase activity apart from its chaperoning function.