Phosphorylation of rat muscle acetyl-CoA carboxylase by AMP-activated protein kinase and protein kinase A
Phosphorylation of rat muscle acetyl-CoA carboxylase by AMP-activated protein kinase and protein kinase A
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DOI：
10.1152/jappl.1997.82.1.219
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发表时间：
1997-01-01
影响因子：
3.3
通讯作者：
Zhou, B
中科院分区：
文献类型：
--
作者：
Winder, WW;Wilson, HA;Zhou, B
本研究旨在比较腺苷3 '，5'-环磷酸依赖性蛋白激酶（PKA）和腺苷酸活化蛋白激酶（AMPK）对肌肉乙酰辅酶A羧化酶（ACC）磷酸化的功能影响。肌肉ACC（272 kDa）磷酸化，然后进行十二烷基硫酸钠-聚丙烯酰胺凝胶电泳，然后进行放射自显影。磷酸化的功能影响，通过测量ACC活性在不同浓度的每种底物和柠檬酸盐，酶的激活剂。ATP、乙酰辅酶A和碳酸氢盐的最大速度（V-max）和米氏常数（K-m）不受PKA磷酸化的影响。AMPK的磷酸化增加了ATP和乙酰辅酶A的Km。PKA和AMPK的顺序磷酸化，第一次没有标记，第二次有标记，似乎降低了标记掺入的程度，无论顺序如何。柠檬酸盐活化的活化常数（K-a）通过AMPK磷酸化增加至相同程度，而不管之前或随后通过PKA的磷酸化。因此，肌肉ACC可以被PKA磷酸化，但对酶没有明显的功能影响。AMPK似乎是肌肉ACC的更重要的调节剂。
This study was designed to compare functional effects of phosphorylation of muscle acetyl-CoA carboxylase (ACC) by adenosine 3',5'-cyclic monophosphate-dependent protein kinase (PKA) and by AMP-activated protein kinase (AMPK). Muscle ACC (272 kDa) was phosphorylated and then subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis followed by autoradiography. Functional effects of phosphorylation were determined by measuring ACC activity at different concentrations of each of the substrates and of citrate, an activator of the enzyme. The maximal velocity (V-max) and the Michaelis constants (K-m) for ATP, acetyl-CoA, and bicarbonate were unaffected by phosphorylation by PKA. Phosphorylation by AMPK increased the K-m for ATP and acetyl-CoA. Sequential phosphorylation by PKA and AMPK, first without label and second with label, appeared to reduce the extent of label incorporation, regardless of the order. The activation constant (K-a) for citrate activation was increased to the same extent by AMPK phosphorylation, regardless of previous or subsequent phosphorylation by PKA. Thus muscle ACC can be phosphorylated by PKA but with no apparent functional effects on the enzyme. AMPK appears to be the more important regulator of muscle ACC.