Lochhead Pamela A, Sibbet Gary, Morrice Nick, Cleghon Vaughn
The Beatson Institute for Cancer Research, Garscube Estate, Switchback Road, Glasgow G61 1BD, Scotland, United Kingdom.
Cell. 2005 Jun 17;121(6):925-36. doi: 10.1016/j.cell.2005.03.034.
Autophosphorylation of a critical residue in the activation loop of several protein kinases is an essential maturation event required for full enzyme activity. However, the molecular mechanism by which this happens is unknown. We addressed this question for two dual-specificity tyrosine-phosphorylation-regulated protein kinases (DYRKs), as they autophosphorylate their activation loop on an essential tyrosine but phosphorylate their substrates on serine and threonine. Here we demonstrate that autophosphorylation of the critical activation-loop tyrosine is intramolecular and mediated by the nascent kinase passing through a transitory intermediate form. This DYRK intermediate differs in residue and substrate specificity, as well as sensitivity to small-molecule inhibitors, compared with its mature counterpart. The intermediate's characteristics are lost upon completion of translation, making the critical tyrosine autophosphorylation a "one-off" inceptive event. This mechanism is likely to be shared with other kinases.
几种蛋白激酶激活环中关键残基的自磷酸化是酶完全活性所需的重要成熟事件。然而，其发生的分子机制尚不清楚。我们针对两种双特异性酪氨酸磷酸化调节蛋白激酶（DYRKs）解决了这个问题，因为它们在关键酪氨酸上自磷酸化其激活环，但在丝氨酸和苏氨酸上磷酸化其底物。在这里，我们证明关键激活环酪氨酸的自磷酸化是分子内的，并且由新生激酶通过一种过渡中间形式介导。与成熟对应物相比，这种DYRK中间体在残基和底物特异性以及对小分子抑制剂的敏感性方面有所不同。翻译完成后，中间体的特征消失，使得关键酪氨酸自磷酸化成为一个“一次性”的起始事件。这种机制可能与其他激酶共有。
