Houston B, Nimmo H G
Biochim Biophys Acta. 1985 Feb 21;844(2):233-9. doi: 10.1016/0167-4889(85)90095-3.
Homogeneous rat liver ATP-citrate lyase (EC 4.1.3.8) was phosphorylated by the catalytic subunit of cAMP-dependent protein kinase. In agreement with other workers, the maximum level of phosphorylation that we observed was approx. 2 mol/mol of tetramer. Phosphorylated and non-phosphorylated forms of ATP-citrate lyase were prepared. Their kinetic properties were examined using an assay system in which the concentrations of Mg.ATP, magnesium.citrate and CoA were varied systematically at a constant concentration of Mg2+. The phosphorylated form had a two-fold higher Km for Mg.ATP than did the non-phosphorylated form, but no other kinetic differences between the two forms were detected. When ATP-citrate lyase was assayed at a concentration of Mg.ATP well below Km, it was found that phosphorylation of the enzyme correlated well with a decrease of approx. 50% in its activity. This is the first demonstration that phosphorylation can affect the activity of ATP-citrate lyase.
均质大鼠肝脏ATP-柠檬酸裂解酶（EC 4.1.3.8）被环磷酸腺苷依赖性蛋白激酶的催化亚基磷酸化。与其他研究者一致，我们观察到的最大磷酸化水平约为每摩尔四聚体2摩尔。制备了ATP-柠檬酸裂解酶的磷酸化形式和非磷酸化形式。使用一种测定系统检查它们的动力学性质，在该系统中，Mg.ATP、柠檬酸镁和辅酶A的浓度在Mg2+浓度恒定的情况下系统地变化。磷酸化形式对Mg.ATP的Km值比非磷酸化形式高两倍，但未检测到两种形式之间的其他动力学差异。当在远低于Km的Mg.ATP浓度下测定ATP-柠檬酸裂解酶时，发现该酶的磷酸化与活性降低约50%密切相关。这是首次证明磷酸化可影响ATP-柠檬酸裂解酶的活性。
