The nuclear matrix protein NMP-1 is the transcription factor YY1.

NMP-1 was initially identified as a nuclear matrix-associated DNA-binding factor that exhibits sequence-specific recognition for the site IV regulatory element of a histone H4 gene. This distal promoter domain is a nuclear matrix interaction site. In the present study, we show that NMP-1 is the multifunctional transcription factor YY1. Gel-shift and Western blot analyses demonstrate that NMP-1 is immunoreactive with YY1 antibody. Furthermore, purified YY1 protein specifically recognizes site IV and reconstitutes the NMP-1 complex. Western blot and gel-shift analyses indicate that YY1 is present within the nuclear matrix. In situ immunofluorescence studies show that a significant fraction of YY1 is localized in the nuclear matrix, principally but not exclusively associated with residual nucleoli. Our results confirm that NMP-1/YY1 is a ubiquitous protein that is present in both human cells and in rat osteosarcoma ROS 17/2.8 cells. The finding that NMP-1 is identical to YY1 suggests that this transcriptional regulator may mediate gene-matrix interactions. Our results are consistent with the concept that the nuclear matrix may functionally compartmentalize the eukaryotic nucleus to support regulation of gene expression. IMAGES:

NMP-1最初被鉴定为一种核基质相关DNA结合因子，可对组蛋白H4基因的位点IV调控元件产生序列特异性识别。该远端启动子结构域是核基质相互作用位点。本研究证实，NMP-1即为多功能转录因子YY1。凝胶迁移实验与蛋白质印迹分析结果显示，NMP-1可与YY1抗体发生免疫反应。此外，纯化的YY1蛋白可特异性识别位点IV，并重建NMP-1复合物。蛋白质印迹与凝胶迁移实验表明，YY1存在于核基质中。原位免疫荧光研究显示，大部分YY1定位于核基质，主要但并非仅与残留核仁相关联。本研究结果证实，NMP-1/YY1是一种遍在蛋白，广泛存在于人类细胞与大鼠骨肉瘤ROS 17/2.8细胞中。此次发现NMP-1与YY1为同一蛋白，提示该转录调控因子可能介导基因与基质之间的相互作用。本研究结果与“核基质可通过功能区室化真核细胞核，以支持基因表达调控”这一概念相符。图像资料：