Moerman A M, Klein C
Cellular and Molecular Biology Graduate Training Program, St. Louis University School of Medicine, 1402 South Grand Boulevard, St. Louis, MO 63104, USA.
Chromosoma. 1998 Jun;107(3):145-54. doi: 10.1007/s004120050291.
Hsp32 is a small shock protein in Dictyostelium discoideum that is expressed in growing cells in the absence of heat shock. Here we show that Hsp32 is an Ag-NOR-staining protein capable of binding DNA with high affinity. Hsp32 is also shown to be a resident nucleolar protein both under normal growth conditions and during heat stress. In unstressed cells, Hsp32 localizes to the nucleolar periphery in a pattern reminiscent of the rDNA in this organism. During the first several hours of heat shock, the peripheral localization of Hsp32 is not altered, although rDNA transcription is arrested. Prolonged heat shock causes a condensation of the rDNA. Under these conditions, Hsp32 is no longer predominantly associated with the rDNA, but is instead distributed over the entire nucleolus. Hsp32 therefore retains ist nucleolar localization under prolonged heat shock conditions by associating with nucleolar components other than the rDNA or rRNA.
Hsp32是盘基网柄菌中的一种小分子应激蛋白，在无热激的生长细胞中表达。我们在此表明，Hsp32是一种能够与DNA高亲和力结合的银染核仁组织区蛋白。在正常生长条件和热应激期间，Hsp32也被证明是一种核仁驻留蛋白。在未受应激的细胞中，Hsp32以一种让人联想到该生物体中核糖体DNA的模式定位于核仁周边。在热激的最初几个小时，尽管核糖体DNA转录被阻断，但Hsp32的周边定位并未改变。长时间热激会导致核糖体DNA凝聚。在这些条件下，Hsp32不再主要与核糖体DNA相关，而是分布在整个核仁中。因此，Hsp32通过与核糖体DNA或核糖体RNA以外的核仁成分结合，在长时间热激条件下保持其核仁定位。
