THE BINDING AND RELEASE OF THE INHIBITOR PROTEIN ARE GOVERNED INDEPENDENTLY BY ATP AND MEMBRANE-POTENTIAL IN OX-HEART SUBMITOCHONDRIAL VESICLES
THE BINDING AND RELEASE OF THE INHIBITOR PROTEIN ARE GOVERNED INDEPENDENTLY BY ATP AND MEMBRANE-POTENTIAL IN OX-HEART SUBMITOCHONDRIAL VESICLES
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DOI：
10.1016/0005-2728(88)90051-5
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发表时间：
1988-03-30
期刊：
影响因子：
--
通讯作者：
HARRIS, DA
中科院分区：
文献类型：
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作者：
LIPPE, G;SORGATO, MC;HARRIS, DA
(1)膜电位（Δ. psi.）和核苷酸对牛心亚线粒体囊泡中F1-ATP合酶及其天然抑制蛋白（IF 1）相互作用的影响。(2)膜电位引起IF 1从亚线粒体囊泡的位移，如通过测量Δ Δ和Δ所示。psi.- ATP酶能力的依赖性刺激和125 I标记的IF 1从囊泡中的释放。如果在孵育中加入ATP，则这些效应消失。(3)氧化囊泡的稳态ATP酶能力线性增加为Δ。psi.从100 mV增加到135 mV。增加Δpsi.高于140 mV不会导致进一步的变化。(4)在恒定的膜电位下，ATP抑制ATP酶能力的增加，半数最大效应的浓度为140 μ M。该值接近膜结合F1对ATP水解的Km。这种抑制与ATP浓度有关，而与Δ Gp或ATP/ADP比无关。(5)分别测量IF 1的单向结合和解离速率。IF 1的解离速率受膜电位的影响而增加，但不受ATP的影响。相反，ATP增加了结合率。因此，抑制潜在的依赖性净释放IF 1从亚线粒体囊泡ATP的结果从IF 1的上速率高于关闭速率的增加。
(1) The effects of membrane potential (.DELTA..psi.) and nucleotides on the interaction between the F1-ATP synthase and its natural inhibitor protein (IF1) are studied in ox-heart submitochondrial vesicles. (2) Membrane potential causes displacement of IF1 from submitochondrial vesicles, as shown by measuring both .DELTA..psi.-dependent stimulation of ATPase capacity and release of 125I-labelled IF1 from the vesicles. These effects are abolished if ATP is included in the incubation. (3) There is a linear increase in the steady-state ATPase capacity of oxidising vesicles as .DELTA..psi. is increased from 100 mV to 135 mV. Increasing .DELTA..psi. above 140 mV leads to no further change. (4) At a constant membrane potential, ATP suppresses the increase in ATPase capacity, with a concentration for half maximal effect of 140 .mu.M. This value is close to the Km for ATP hydrolysis by membrane-bound F1. This suppression is related to ATP concentrations rather than to .DELTA.Gp or ATP/ADP ratio. (5) The unidirectional on- and off-rates of IF1 were measured separately. The off-rate of IF1 is increased by membrane potential but unaffected by ATP. The on-rate, conversely, is increased by ATP. Thus, the suppression of the potential-dependent net release of IF1 from submitochondrial vesicles by ATP results from an increase of the IF1 on-rate above the off-rate.