A high-affinity, calmodulin-sensitive (Ca2+ + Mg2+)-ATPase and associated calcium-transport pump in the Ehrlich ascites tumor cell plasma membrane.
A high-affinity, calmodulin-sensitive (Ca2+ + Mg2+)-ATPase and associated calcium-transport pump in the Ehrlich ascites tumor cell plasma membrane.
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艾利希腹水肿瘤细胞质膜中的高亲和力、钙调蛋白敏感 (Ca2 Mg2 )-ATP 酶和相关钙转运泵。
DOI：
10.1016/0003-9861(83)90331-4
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发表时间：
1983
影响因子：
3.9
通讯作者：
McDonald,JM
中科院分区：
文献类型：
--
作者：
Klaven,NB;Pershadsingh,HA;Henius,GV;Laris,PC;LongJr,JW;McDonald,JM
从艾氏腹水肿瘤细胞(G.V.Henius，P.C.Laris和J.D.Woodburn(1979)Exp.牢房。结果121,337-345)被用来鉴定高亲和力质膜钙挤压泵及其相关的三磷酸腺苷酶(ATPase)。该钙转运系统对游离钙有很高的亲和力(K0.5=0.040±0.005μM)。检测到两种不同的钙刺激的ATPase活性。一个对游离钙具有低亲和力(K0.5=136±10μM)，另一个具有高亲和力(K0.5=0.103±0.077μM)。这种高亲和力酶似乎代表了正常细胞中普遍存在的高亲和力质膜(Ca~(2+)+Mg~(2+))-ATPase(钙刺激、镁依赖的ATPase)。钙依赖调节蛋白钙调蛋白对钙转运和(Ca~(2+)-Mg~(2+)-ATPase)-ATPase均有显著的刺激作用，尤其是用钙离子螯合剂乙二醇双(β-氨基乙醚)N，N‘-四乙酸去掉内源性激活剂时。钙转运和(Ca2++Mg2+)-ATPase之间的其他相似之处包括对哇巴因(0.5 mM)不敏感，钾(20 MM)缺乏激活，以及对镁的需求。这些相似的性质表明，(Ca~(2+)+Mg~(2+))-ATPase是高亲和力钙泵的酶基础。较高浓度(钙转运：K0.5−100μM；(Ca~(2+)+Mg~(2+))-ATP酶：K0.5>；100μM)对钙泵/酶系统有抑制作用。Hill分析表明，肿瘤细胞(Ca~(2+)+Mg~(2+))-ATPase不能被钙协同激活，这是正常细胞质膜中类似酶的特征。
A unique cytoplast preparation from Ehrlich ascites tumor cells (G. V. Henius, P. C. Laris, and J. D. Woodburn (1979)Exp. Cell. Res.121, 337–345), highly enriched in plasma membranes, was employed to characterize the high-affinity plasma membrane calcium-extrusion pump and its associated adenosine triphosphatase (ATPase). An ATP-dependent calcium-transport system which had a high affinity for free calcium (K0.5= 0.040 ± 0.005μM) was identified. Two different calcium-stimulated ATPase activities were detected. One had a low (K0.5= 136 ± 10μM) and the other a high (K0.5= 0.103 ± 0.077μM) affinity for free calcium. The high-affinity enzyme appeared to represent the ubiquitous high-affinity plasma membrane (Ca2++ Mg2+)-ATPase (calcium-stimulated, magnesium-dependent ATPase) seen in normal cells. Both calcium transport and the (Ca2++ Mg2+)-ATPase were significantly stimulated by the calcium-dependent regulatory protein calmodulin, especially when endogenous activator was removed by treatment with the calcium chelator ethylene glycol bis(β-aminoethyl ether)N, N′-tetraacetic acid. Other similarities between calcium transport and the (Ca2++ Mg2+)-ATPase included an insensitivity to ouabain (0.5 mm), lack of activation by potassium (20 mm) and a requirement for magnesium. These similar properties suggested that the (Ca2++ Mg2+)-ATPase represents the enzymatic basis of the high-affinity calcium pump. The calcium pump/enzyme system was inhibited by orthovanadate at comparatively high concentrations (calcium transport:K0.5− 100μM; (Ca2++ Mg2+)-ATPase:K0.5> 100μM). Upon Hill analysis, the tumor cell (Ca2++ Mg2+)-ATPase failed to exhibit cooperative activation by calcium which is characteristic of the analogous enzyme in the plasma membrane of normal cells.