The amino-terminal 200 amino acids of the plasma membrane Na+,K+-ATPase alpha subunit confer ouabain sensitivity on the sarcoplasmic reticulum Ca(2+)-ATPase.
The amino-terminal 200 amino acids of the plasma membrane Na+,K+-ATPase alpha subunit confer ouabain sensitivity on the sarcoplasmic reticulum Ca(2+)-ATPase.
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质膜 Na ,K -ATP 酶 α 亚基的氨基末端 200 个氨基酸赋予哇巴因对肌浆网 Ca(2 ) -ATP 酶的敏感性。
DOI：
10.1073/pnas.90.19.8881
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发表时间：
1993
影响因子：
11.1
通讯作者：
Takeyasu,K
中科院分区：
文献类型：
--
作者：
Ishii,T;Takeyasu,K
强心苷如 G-stropanthin (ouabain) 结合并抑制质膜 Na+,K(+)-ATPase，但不抑制肌浆网 (SR) Ca(2+)-ATPase，而毒胡萝卜素特异性阻断 SR Ca(2+)-ATPase。嵌合体[n/c]CC，其中SR Ca(2+)-ATP酶(SERCA1)的氨基末端氨基酸Met1至Asp162被Na+,K(+)-ATP酶α1亚基的相应部分(Met1至Asp200)替换，保留了毒胡萝卜素和Ca(2+)敏感性ATP酶活性，尽管其活性低于野生型SR Ca(2+)-ATP 酶。此外，这种 Ca(2+) 敏感的 ATP 酶活性受到哇巴因的抑制。嵌合体NCC，其中SR Ca(2+)-ATP酶的Met1-Gly354被Na+,K(+)-ATP酶的相应部分取代，失去了CCC和[n/c]CC中观察到的毒胡萝卜素敏感的Ca(2+)-ATP酶活性。 [3H]哇巴因与[n/c]CC和NCC的结合表明，在这些嵌合分子中恢复了在野生型鸡Na+,K(+)-ATP酶中观察到的对该抑制剂的亲和力。因此，哇巴因结合域不同于毒胡萝卜素位点；哇巴因与 Na+,K(+)-ATPase α 1 亚基的氨基末端部分（Met1 至 Asp200）结合，而毒胡萝卜素与 Ca(2+)-ATPase 的 Asp162 之后的区域相互作用。此外，Na+,K(+)-ATPase α 1 亚基的氨基末端 200 个氨基酸即使在掺入 Ca(2+)-ATPase 的相应部分后也足以发挥哇巴因依赖性抑制作用，并且 SR Ca(2+)-ATPase 的 Ile163 至 Gly354 片段对于毒胡萝卜素和 Ca(2+) 敏感的 ATPase 活性至关重要。
Cardiac glycosides such as G-strophanthin (ouabain) bind to and inhibit the plasma membrane Na+,K(+)-ATPase but not the sarcoplasmic reticulum (SR) Ca(2+)-ATPase, whereas thapsigargin specifically blocks the SR Ca(2+)-ATPase. The chimera [n/c]CC, in which the amino-terminal amino acids Met1 to Asp162 of the SR Ca(2+)-ATPase (SERCA1) were replaced with the corresponding portion of the Na+,K(+)-ATPase alpha 1 subunit (Met1 to Asp200), retained thapsigargin- and Ca(2+)-sensitive ATPase activity, although the activity was lower than that of the wild-type SR Ca(2+)-ATPase. Moreover, this Ca(2+)-sensitive ATPase activity was inhibited by ouabain. The chimera NCC, in which Met1-Gly354 of the SR Ca(2+)-ATPase were replaced with the corresponding portion of the Na+,K(+)-ATPase, lost the thapsigargin-sensitive Ca(2+)-ATPase activity seen in CCC and [n/c]CC. [3H]Ouabain binding to [n/c]CC and NCC demonstrated that the affinity for this inhibitor seen in the wild-type chicken Na+,K(+)-ATPase was restored in these chimeric molecules. Thus, the ouabain-binding domains are distinct from the thapsigargin sites; ouabain binds to the amino-terminal portion (Met1 to Asp200) of the Na+,K(+)-ATPase alpha 1 subunit, whereas thapsigargin interacts with the regions after Asp162 of the Ca(2+)-ATPase. Moreover, the amino-terminal 200 amino acids of the Na+,K(+)-ATPase alpha 1 subunit are sufficient to exert ouabain-dependent inhibition even after incorporation into the corresponding portion of the Ca(2+)-ATPase, and the segment Ile163 to Gly354 of the SR Ca(2+)-ATPase is critical for thapsigargin- and Ca(2+)-sensitive ATPase activity.