| Item type |
学術雑誌論文 / Journal Article_02(1) |
| 公開日 |
2009-03-11 |
| タイトル |
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タイトル |
Roles of Tyr122-hydrophobic cluster and K+ binding in Ca2+ -releasing process of ADP-insensitive phosphoenzyme of sarcoplasmic reticulum Ca2+ -ATPase |
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言語 |
en |
| 言語 |
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言語 |
eng |
| 資源タイプ |
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資源タイプ |
journal article |
| 著者 |
山崎, 和生
Wang, G
Daiho, T
Danko, S
Suzuki, H
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| 著者 ローマ字 |
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Yamasaki, Kazuo |
| 書誌情報 |
Journal of Biological Chemistry
巻 283,
号 43,
p. 29144-29155,
発行日 2008-10-01
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| ISSN |
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収録物識別子タイプ |
ISSN |
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収録物識別子 |
0021-9258 |
| DOI |
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関連タイプ |
isVersionOf |
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識別子タイプ |
DOI |
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関連識別子 |
10.1074/jbc.M804596200 |
| リンクURL |
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内容記述タイプ |
Other |
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内容記述 |
http://www.ncbi.nlm.nih.gov/pubmed/18728008 | http://www.ncbi.nlm.nih.gov/pubmed/18728008 |
| 抄録 |
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内容記述タイプ |
Abstract |
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内容記述 |
Tyr(122)-hydrophobic cluster (Y122-HC) is an interaction network formed by the top part of the second transmembrane helix and the cytoplasmic actuator and phosphorylation domains of sarcoplasmic reticulum Ca(2+)-ATPase. We have previously found that Y122-HC plays critical roles in the processing of ADP-insensitive phosphoenzyme (E2P) after its formation by the isomerization from ADP-sensitive phosphoenzyme (E1PCa(2)) (Wang, G., Yamasaki, K., Daiho, T., and Suzuki, H. (2005) J. Biol. Chem. 280, 26508-26516). Here, we further explored kinetic properties of the alanine-substitution mutants of Y122-HC to examine roles of Y122-HC for Ca(2+) release process in E2P. In the steady state, the amount of E2P decreased so that of E1PCa(2) increased with increasing lumenal Ca(2+) concentration in the mutants with K(0.5) 110-320 microm at pH 7.3. These lumenal Ca(2+) affinities in E2P agreed with those estimated from the forward and lumenal Ca(2+)-induced reverse kinetics of the E1PCa(2)-E2P isomerization. K(0.5) of the wild type in the kinetics was estimated to be 1.5 mM. Thus, E2P of the mutants possesses significantly higher affinities for lumenal Ca(2+) than that of the wild type. The kinetics further indicated that the rates of lumenal Ca(2+) access and binding to the transport sites of E2P were substantially slowed by the mutations. Therefore, the proper formation of Y122-HC and resulting compactly organized structure are critical for both decreasing Ca(2+) affinity and opening the lumenal gate, thus for Ca(2+) release from E2PCa(2). Interestingly, when K(+) was omitted from the medium of the wild type, the properties of the wild type became similar to those of Y122-HC mutants. K(+) binding likely functions via producing the compactly organized structure, in this sense, similarly to Y122-HC. |
| 注記 |
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内容記述タイプ |
Other |
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注記 |
author |
| 資源タイプ |
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内容記述タイプ |
Other |
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資源タイプ |
text |
| 著者版フラグ |
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出版タイプ |
AM |
| フォーマット |
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内容記述タイプ |
Other |
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内容記述 |
application/pdf |
| ID(XooNIps) |
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18728008 |
| 閲覧数(XooNIps) |
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| ダウンロード数(XooNIps) |
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1255 |
1605.pdf (3.8 MB)
