Zhang P, Davis A T, Ahmed K
Department of Laboratory Medicine and Pathology, University of Minnesota, Minneapolis 55417, USA.
J Cell Biochem. 1998 May 1;69(2):211-20.
Nuclear matrix (NM) appears to be an intranuclear locale for significant and dynamic association of the ubiquitous multifunctional messenger-independent serine/threonine protein kinase CK2 that has been implicated in growth control [Tawfic et al. (1996): J Cell Biochem 61:165-171]. We have examined the nature of the association of CK2 with the NM. Nuclei prepared in the presence of a sulfhydryl-blocking reagent such as iodoacetamide demonstrate a reduction in the amount of CK2 associated with the NM to less than 5% of the control. On the other hand, when nuclei are treated with the sulfhydryl crosslinking reagent sodium tetrathionate, NM-associated CK2 increases severalfold. Treatment of nuclei with sodium tetrathionate followed by 2-mercaptoethanol blocks this increase. Nuclei isolated from rat liver and prostate behaved similarly, suggesting an identical mode of association of CK2 with the NM regardless of the organ. These results indicate a role of sulfhydryl interactions such that NM anchoring of CK2 occurs via its beta subunit, which contains several vicinal cysteine residues. Further, various sulfhydryl-blocking reagents inhibited CK2 activity in a concentration-dependent manner, and the inhibitory effect was reversed by agents such as dithiothreitol, implying that cysteine residues in the CK2 play a role in its catalytic activity.
核基质（NM）似乎是普遍存在的多功能非信使依赖型丝氨酸/苏氨酸蛋白激酶CK2进行重要且动态结合的核内场所，该激酶与生长调控有关[陶菲克等人（1996年）：《细胞生物化学杂志》61卷：165 - 171页]。我们已经研究了CK2与核基质结合的性质。在存在诸如碘乙酰胺等巯基阻断剂的情况下制备的细胞核，显示与核基质结合的CK2量减少至对照的不到5%。另一方面，当用巯基交联剂连四硫酸钠处理细胞核时，与核基质相关的CK2增加了几倍。先用连四硫酸钠处理细胞核，然后用2 - 巯基乙醇处理，可阻断这种增加。从大鼠肝脏和前列腺分离的细胞核表现相似，这表明无论器官如何，CK2与核基质的结合模式相同。这些结果表明巯基相互作用的作用，即CK2通过其含有几个相邻半胱氨酸残基的β亚基锚定在核基质上。此外，各种巯基阻断剂以浓度依赖的方式抑制CK2活性，并且诸如二硫苏糖醇等试剂可逆转这种抑制作用，这意味着CK2中的半胱氨酸残基在其催化活性中起作用。
