Guerra B, Issinger O G
Biokemisk Institut, Odense Universitet, Denmark.
Electrophoresis. 1999 Feb;20(2):391-408. doi: 10.1002/(SICI)1522-2683(19990201)20:2<391::AID-ELPS391>3.0.CO;2-N.
Protein kinase CK2 is a pleiotropic, ubiquitous and constitutively active protein kinase that can use both ATP and GTP as phosphoryl donors with specificity for serine/threonine residues in the vicinity of acidic amino acids. Recent results show that the enzyme is involved in transcription, signaling, proliferation and in various steps of development. The tetrameric holoenzyme (alpha2beta2) consists of two catalytic alpha-subunits and two regulatory beta-subunits. The structure of the catalytic subunit with the fixed positioning of the activation segment in the active conformation through its own aminoterminal region suggests a regulation at the transcriptional level making a regulation by second messengers unlikely. The high conservation of the catalytic subunit from yeast to man and its role in the tetrameric complex supports this notion. The regulatory beta-subunit has been far less conserved throughout evolution. Furthermore the existence of different CK2beta-related proteins together with the observation of deregulated CK2beta levels in tumor cells and the reported association of CK2beta protein with key proteins in signal transduction, e.g. A-Raf, Mos, pg90rsk etc. are suggestive for an additional physiological role of CK2beta protein beside being the regulatory compound in the tetrameric holoenzyme.
蛋白激酶CK2是一种多效性、普遍存在且组成型激活的蛋白激酶，它既能将ATP也能将GTP用作磷酰基供体，对酸性氨基酸附近的丝氨酸/苏氨酸残基具有特异性。最近的研究结果表明，该酶参与转录、信号传导、增殖以及发育的各个阶段。四聚体全酶（α2β2）由两个催化性α亚基和两个调节性β亚基组成。催化亚基的结构通过其自身的氨基末端区域在活性构象中使激活片段固定定位，这表明在转录水平上存在调节，不太可能通过第二信使进行调节。从酵母到人催化亚基的高度保守性及其在四聚体复合物中的作用支持了这一观点。调节性β亚基在整个进化过程中的保守性要低得多。此外，不同的CK2β相关蛋白的存在，以及在肿瘤细胞中观察到的CK2β水平失调，以及报道的CK2β蛋白与信号转导中的关键蛋白（如A-Raf、Mos、pg90rsk等）的关联，表明CK2β蛋白除了作为四聚体全酶中的调节化合物之外，还具有额外的生理作用。
