Separation of two phosphorylase kinase phosphatases from rabbit skeletal muscle.
Separation of two phosphorylase kinase phosphatases from rabbit skeletal muscle.
复制标题
从兔骨骼肌中分离两种磷酸化酶激酶磷酸酶。
DOI：
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发表时间：
1976
期刊：
影响因子：
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通讯作者：
P. Cohen
中科院分区：
文献类型：
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作者：
J. Antoniw;P. Cohen
环磷酸腺苷依赖性蛋白激酶催化磷酸化酶激酶的活化和磷酸化酶激酶α亚基和β亚基上两个丝氨酸残基的磷酸化[Cohen， P., Watson， D.C.和Dixon， G.H.(1975)]。磷酸化酶激酶的去磷酸化被两种不同的酶催化，称为α -磷酸化酶激酶磷酸酶和β -磷酸化酶激酶磷酸酶。这两种酶分别对α和β亚基表现出绝对的特异性。两种磷酸酶经乙醇分馏法、deae -纤维素层析法和硫酸铵沉淀法共纯化，在Sephadex G-200上用凝胶过滤分离。α -磷酸化酶激酶磷酸酶在乙醇沉淀步骤中纯化500倍，β -磷酸化酶激酶磷酸酶纯化320倍。凝胶过滤估计α -磷酸化酶激酶磷酸酶的分子量为170—180000，β -磷酸化酶激酶磷酸酶的分子量为75—80000。由于磷酸化酶激酶的活性与β亚基的磷酸化状态相关（Cohen， P.(1974)），因此β -磷酸化酶激酶磷酸酶是逆转磷酸化酶激酶活化的酶。α -磷酸化酶激酶磷酸酶是一种以前未被认识到的酶活性。由于α -亚基磷酸化的作用是刺激β -亚基去磷酸化的速率（Cohen， P.(1974)），因此α -磷酸化酶激酶磷酸酶可被视为抑制磷酸化酶激酶活化逆转的酶。这些发现的意义的磷酸化酶激酶活性的多位点磷酸化激素控制进行了讨论。
Cyclic-AMP-dependent protein kinase catalyses the activation of phosphorylase kinase and the phosphorylation of two serine residues on the alpha subunit and beta subunit of phosphorylase kinase [Cohen, P., Watson, D.C. and Dixon, G.H. (1975)]. The dephosphorylation of phosphorylase kinase has been shown to be catalysed by two distinct enzymes, termed alpha-phosphorylase kinase phosphatase and beta-phosphorylase kinase phosphatase. These two enzymes show essentially absolute specificity towards the alpha and beta subunits respectively. The two phosphatases copurified through ethanol fractionation, DEAE-cellulose chromatography and ammonium sulphate precipitation, but were separated from each other by a gel filtration on Sephadex G-200. alpha-Phosphorylase kinase phosphatase was purified 500-fold from the ethanol precipitation step, and beta-phosphorylase kinase phosphatase 320-fold. The molecular weights estimated by gel filtration were 170--180 000 for alpha-phosphorylase kinase phosphatase and 75--80 000 for beta-phosphorylase kinase phosphatase. Since the activity of phosphorylase kinase correlates with the state of phosphorylation of the beta subunit (Cohen, P. (1974)), beta-phosphorylase kinase phosphatase is the enzyme which reverses the activation of phosphorylase kinase. alpha-Phosphorylase kinase phosphatase is an enzyme activity that has not been recognised previously. Since the role of the alpha-subunit phosphorylation is to stimulate the rate of dephosphorylation of the beta subunit (Cohen, P. (1974)), alpha-phosphorylase kinase phosphatase can be regarded as the enzyme which inhibits the reversal of the activation of phosphorylase kinase. The implications of these findings for the hormonal control of phosphorylase kinase activity by multisite phosphorylation are discussed.