Tsimokha A S, Vatazhok Iu Ia, Vashukova E S, Kulichkova V A, Volkova I V, Ermolaeva Iu B, Mittenberg A G, Evteeva I N, Ivanov V A, Gauze L N, Konstantinova I M
Tsitologiia. 2005;47(5):436-41.
In eukaryotic cells the population of proteasomes is heterogeneous. Here we have shown that proteasomes from nuclei and cytoplasm of rat liver cells differ in their subunit patterns. The subunit pattern of alpha-RNP differs from that of proteasomes, however, alpha-RNP particles contain the number of 26S proteasome subunits. Moreover, the proteasomes contain subunits of alpha-RNP. We have shown for the first time that nuclear proteasomes and alpha-RNP are hyperphosphorylated on threonine residues. Differences in phosphorylation state of subunits of nuclear and cytoplasmic proteasomes and alpha-RNP on threonine and tyrosine residues have been revealed. A suggestion is put forward that hyperphosphorylation of subunits may determine nuclear localization of these complexes in rat liver cells. The results obtained suggest that a highly specialized system of protein kinases and phosphatases may be involved in the regulation of phosphorylation state of different populations of proteasomes and alpha-RNP in rat liver cells.
在真核细胞中，蛋白酶体群体是异质的。我们在此表明，大鼠肝细胞细胞核和细胞质中的蛋白酶体在其亚基模式上存在差异。α-RNP的亚基模式与蛋白酶体不同，然而，α-RNP颗粒含有26S蛋白酶体亚基的数量。此外，蛋白酶体含有α-RNP的亚基。我们首次表明，核蛋白酶体和α-RNP在苏氨酸残基上发生了过度磷酸化。已揭示出核和细胞质蛋白酶体以及α-RNP亚基在苏氨酸和酪氨酸残基上的磷酸化状态存在差异。有人提出，亚基的过度磷酸化可能决定了这些复合物在大鼠肝细胞中的核定位。所获得的结果表明，一个高度专业化的蛋白激酶和磷酸酶系统可能参与调节大鼠肝细胞中不同群体的蛋白酶体和α-RNP的磷酸化状态。
