Fox D K, Meadow N D, Roseman S
J Biol Chem. 1986 Oct 15;261(29):13498-503.
Interactions between homogeneous acetate kinase and proteins of the phosphoenolpyruvate:glucose phosphotransferase system (PTS) were studied. The phosphorylation of D-glucose was followed spectrophotometrically using a coupled assay system, and acetate kinase and GTP were found to substitute for phosphoenolpyruvate provided that each of the PTS proteins was present in the mixture. To further define the phosphoryl transfer reaction pathway, the system was simplified to include only the homogeneous, soluble PTS proteins. 32P was transferred from [gamma-32P]ATP to the protein IIIGlc, but this transfer reaction required acetate kinase, and the PTS proteins Enzyme I and HPr. These results suggested that acetate kinase interacts with the first protein in the PTS sequence, Enzyme I. Acetate kinase was therefore incubated with [32P] phospho-Enzyme I, and a direct transfer of the phosphoryl group was observed without the addition of any other protein. These results show that there is a reversible transfer of the phosphoryl group between Enzyme I and acetate kinase. The possible role of this interaction in regulating sugar uptake by the Krebs cycle is discussed.
葡萄糖磷酸转移酶系统（PTS）的蛋白质之间的相互作用。使用偶联测定系统通过分光光度法跟踪D-葡萄糖的磷酸化，并且发现只要混合物中存在每种PTS蛋白质，乙酸激酶和GTP就可以替代磷酸烯醇丙酮酸。为了进一步确定磷酰基转移反应途径，将该系统简化为仅包括均一的可溶性PTS蛋白质。32P从[γ-32P]ATP转移至蛋白质IIIGlc，但该转移反应需要乙酸激酶以及PTS蛋白质酶I和HPr。这些结果表明乙酸激酶与PTS序列中的第一个蛋白质酶I相互作用。因此，将乙酸激酶与[32P]磷酸化酶I一起孵育，并且在不添加任何其他蛋白质的情况下观察到磷酰基的直接转移。这些结果表明在酶I和乙酸激酶之间存在磷酰基的可逆转移。讨论了这种相互作用在调节克雷布斯循环对糖的摄取中的可能作用。
