High mobility group 1 protein is not stably associated with the chromosomes of somatic cells.
High mobility group 1 protein is not stably associated with the chromosomes of somatic cells.
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DOI：
10.1083/jcb.137.1.19
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发表时间：
1997-04-07
期刊：
影响因子：
--
通讯作者：
Bianchi ME
中科院分区：
文献类型：
--
作者：
Falciola L;Spada F;Calogero S;Langst G;Voit R;Grummt I;Bianchi ME
高迁移率组 1 (HMG1) 蛋白是脊椎动物细胞核中丰富且保守的成分，已被认为在染色质组织中发挥结构作用，可能类似于组蛋白 H1。然而，据报道，哺乳动物细胞的细胞质和表面也存在高丰度的 HMG1。我们最终证明 HMG1 是一种核蛋白，因为几种不同的抗 HMG1 抗体会对培养细胞的核质进行染色，并且表位标记的 HMG1 仅位于细胞核中。该蛋白质被排除在核仁之外，并且与特定的核结构无关，而是似乎均匀分布。 HMG1 可以在体外与重建的核心核小体结合，但与活细胞中的染色质不稳定相关。在中期，HMG1 与浓缩染色体分离，与组蛋白 H1 相反。在间期期间，用去污剂透化核膜后，HMG1 很容易从细胞核中扩散出来，而组蛋白 H1 仍然与染色质相关。这些特性排除了 HMG1 和 H1 在分化细胞中的共同功能，尽管它们具有相似的生化特性。 HMG1 可能仅与极少数核小体稳定相关，或者可能在染色质重塑的动态过程中与核小体短暂相互作用。
High mobility group 1 (HMG1) protein is an abundant and conserved component of vertebrate nuclei and has been proposed to play a structural role in chromatin organization, possibly similar to that of histone H1. However, a high abundance of HMG1 had also been reported in the cytoplasm and on the surface of mammalian cells. We conclusively show that HMG1 is a nuclear protein, since several different anti-HMG1 antibodies stain the nucleoplasm of cultured cells, and epitope-tagged HMG1 is localized in the nucleus only. The protein is excluded from nucleoli and is not associated to specific nuclear structures but rather appears to be uniformly distributed. HMG1 can bind in vitro to reconstituted core nucleosomes but is not stably associated to chromatin in live cells. At metaphase, HMG1 is detached from condensed chromosomes, contrary to histone H1. During interphase, HMG1 readily diffuses out of nuclei after permeabilization of the nuclear membranes with detergents, whereas histone H1 remains associated to chromatin. These properties exclude a shared function for HMG1 and H1 in differentiated cells, in spite of their similar biochemical properties. HMG1 may be stably associated only to a very minor population of nucleosomes or may interact transiently with nucleosomes during dynamic processes of chromatin remodeling.