Leroy D, Valero E, Filhol O, Heriché J K, Goldberg Y, Chambaz E M, Cochet C
CEA, INSERM Unité 244, DBMS, Grenoble, France.
Cell Mol Biol Res. 1994;40(5-6):441-53.
Polyamines have been reported to stimulate casein kinase 2 (CK2) in vitro. We have shown that the phosphorylation of different substrates is diversely stimulated by basic effectors and that the responsiveness of CK2 activity may be influenced by the overall conformation of the protein substrate but also by a specific interaction with the enzyme itself. Our data show that native hetero tetrameric CK2 is a spermine binding protein and a spermine binding site was identified in the N-terminal region of the beta subunit of CK2. We found that recombinant CK2 undergoes a progressive polymerization in low salt conditions, giving rise to three different polymer structures. A ring-like structure formed by the association of four protomers alpha 2 beta 2 was characterized by gel filtration, sucrose density gradient analysis and electron microscopy. Polyamines like spermine, when added under conditions where the enzyme preparation contains a mixture of various oligomers, could trigger their dissociation and their interconversion in the fully active ring structure. These results suggest that in the presence of positive effectors like polyamines, CK2 adopts a ring-like structural organization which may represent the active state of this kinase.
据报道，多胺在体外可刺激酪蛋白激酶2（CK2）。我们已经表明，碱性效应物对不同底物的磷酸化具有不同的刺激作用，并且CK2活性的反应性可能受蛋白质底物的整体构象影响，也受与酶本身的特异性相互作用影响。我们的数据表明，天然异源四聚体CK2是一种精胺结合蛋白，并且在CK2β亚基的N端区域鉴定出一个精胺结合位点。我们发现重组CK2在低盐条件下会进行逐步聚合，产生三种不同的聚合物结构。通过凝胶过滤、蔗糖密度梯度分析和电子显微镜对由四个原体α2β2缔合形成的环状结构进行了表征。当在酶制剂含有各种寡聚体混合物的条件下添加精胺等多胺时，它们可以触发其解离并使其转化为完全活性的环状结构。这些结果表明，在多胺等正效应物存在的情况下，CK2采用环状结构组织，这可能代表该激酶的活性状态。
