Sul H S, Walsh D A
J Biol Chem. 1982 Sep 10;257(17):10324-8.
We have documented previously that although the phosphorylation of the beta subunit of cardiac phosphorylase kinase plays a major role in activation of the enzyme, enzyme activity is also modulated by either cAMP-dependent or cAMP-independent phosphorylation of the alpha' subunit (Sul, H. S., Cooper R. H., Whitehouse S., and Walsh D. A. (1982) J. Biol. Chem. 257, 3484-3490). This paper reports that deactivation of 32P-labeled cardiac phosphorylase kinase by protein phosphatase occurs concomitantly with the dephosphorylation of either the alpha' or beta subunits. However, enzyme activation attributable to alpha' subunit phosphorylation is still apparent after dephosphorylation of the beta subunit and, similarly, that caused by beta subunit phosphorylation is maintained after alpha' subunit dephosphorylation. These data support out previously stated conclusion that both alpha' and beta subunit phosphorylation regulates the activity of cardiac phosphorylase kinase.
我们之前已证明，尽管心肌磷酸化酶激酶β亚基的磷酸化在该酶的激活中起主要作用，但酶活性也受α'亚基的cAMP依赖性或cAMP非依赖性磷酸化的调节（Sul，H. S.，Cooper R. H.，Whitehouse S.，以及Walsh D. A.（1982年）《生物化学杂志》257卷，3484 - 3490页）。本文报道，蛋白磷酸酶使32P标记的心肌磷酸化酶激酶失活的同时，α'或β亚基会发生去磷酸化。然而，在β亚基去磷酸化后，归因于α'亚基磷酸化的酶激活仍然明显，同样，在α'亚基去磷酸化后，由β亚基磷酸化引起的激活也得以维持。这些数据支持了我们之前提出的结论，即α'和β亚基的磷酸化均调节心肌磷酸化酶激酶的活性。
