(Na+,K+)-ATPase of mammalian brain: differential effects on cation affinities of phosphorylation by ATP and acetylphosphate.
(Na+,K+)-ATPase of mammalian brain: differential effects on cation affinities of phosphorylation by ATP and acetylphosphate.
复制标题
哺乳动物脑的 (Na ,K )-ATP 酶：ATP 和乙酰磷酸对磷酸化阳离子亲和力的不同影响。
DOI：
10.1016/0003-9861(80)90195-2
复制
发表时间：
1980
影响因子：
3.9
通讯作者：
R. Albers
中科院分区：
文献类型：
--
作者：
A. Swann;R. Albers
由于它们不同的浓度依赖关系，(Na+，K+)-ATPase([Na+]0.5=1.5 mM)的磷酸化所需的Na+相互作用与(Na+，K+-ATPase)转化为其高K+亲和力形式([Na+]0.5=6 mM，不含ATP的[Na+]0.5=28 mM)似乎是不同的。这种分布不归因于核苷酸或K+结合的调节。在没有Na+的情况下，乙酰磷酸反应生成一种磷酸化酶，K+只会轻微加速该酶的水解。除Na+外，在相似条件下形成的磷酸酶对K+的加入高度敏感。ATP和乙酰磷酸都与钠协同作用，有利于ATPase以高K+亲和力的形式存在。然而，乙酰磷酸只能通过增加这种形式的酶的比例来起作用，而ATP也会导致[Na+]0.5的减少。以往的研究表明，这种ATP效应是磷酸化酶形成的结果。这些结果表明，Na+结合可能是产生K+敏感的磷酸化酶所必需的，核苷酸结合增加了磷酸化酶的Na+亲和力。
Because of their differing concentration dependencies, the Na+interactions required for the phosphorylation of (Na+,K+)-ATPase ([Na+]0.5= 1.5 mm) and those required for the transformation of (Na+,K+-ATPase into its high-K+affinity form ([Na+]0.5= 6 mmwith ATP and 28 mmwithout ATP) appear to be distinct. This distribution is not attributable to modulation by either nucleotide or K+binding. In the absence of Na+, acetylphosphate reacts to form a phosphorylenzyme the hydrolysis of which is only slightly accelerated by K+. Phosphorylenzyme formed under similar conditions except for the presence of Na+is highly sensitive to the addition of K+. ATP and acetylphosphate both act synergistically with sodium to favor the existence of the ATPase in its high-K+-affinity form. Acetylphosphate, however, acts only by increasing the proportion of enzyme in this form, whereas, ATP also causes a reduction in [Na+]0.5. Previous studies have shown that this ATP effect is a consequence of formation of phosphorylenzyme. Results presented here suggest that Na+binding may be necessary to produce K+-sensitive phosphorylenzyme and that nucleotide binding increases the Na+affinity of phosphorylenzyme.