Yanagi S, Shimbara N, Tamura T a
Department of Biology, Faculty of Science, Chiba University, Japan.
Biochem Biophys Res Commun. 2000 Dec 20;279(2):568-73. doi: 10.1006/bbrc.2000.3969.
The proteasome is an eukaryotic multi-subunit protease complex composed of one 20S core component and two 19S regulatory complexes. The regulatory complex contains 6 putative ATPases. We investigated tissue and cell distribution of one of these ATPases, MSS1 (mammalian suppressor of sgv1). MSS1 was ubiquitously present in rat tissues as was the 20S core component of proteasome. However, the ratio of MSS1 to 20S varied greatly among tissues and MSS1 was concentrated in the thymus. Glycerol gradient sedimentation analysis revealed that MSS1 is included in protein complexes whose density is lighter than that of the proteasome. MSS1 was distributed in mammalian cells ubiquitously, while proteasome was rather concentrated in the nuclei. Hence, a novel molecular status of MSS1 distinct from proteasome is implicated. Interestingly, multiple basal transcription factors for RNA polymerase II, including TBP, TFIIB, TFIIH, and TFIIF, were found to be associated with MSS1. These results suggest that MSS1, in addition to proteolysis, plays a role in DNA metabolism including transcriptional regulation.
蛋白酶体是一种真核多亚基蛋白酶复合物，由一个20S核心组分和两个19S调节复合物组成。调节复合物包含6个假定的ATP酶。我们研究了其中一种ATP酶MSS1（sgv1的哺乳动物抑制因子）的组织和细胞分布。MSS1在大鼠组织中普遍存在，蛋白酶体的20S核心组分也是如此。然而，MSS1与20S的比例在不同组织中差异很大，且MSS1集中在胸腺中。甘油梯度沉降分析表明，MSS1包含在密度比蛋白酶体轻的蛋白质复合物中。MSS1在哺乳动物细胞中普遍分布，而蛋白酶体则相对集中在细胞核中。因此，暗示了MSS1与蛋白酶体不同的新分子状态。有趣的是，发现包括TBP、TFIIB、TFIIH和TFIIF在内的多种RNA聚合酶II的基础转录因子与MSS1相关。这些结果表明，MSS1除了参与蛋白水解外，还在包括转录调控在内的DNA代谢中发挥作用。
