Whitfield Michael L, Kaygun Handan, Erkmann Judith A, Townley-Tilson W H Davin, Dominski Zbigniew, Marzluff William F
Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, NC 27599, USA.
Nucleic Acids Res. 2004 Sep 9;32(16):4833-42. doi: 10.1093/nar/gkh798. Print 2004.
The stem-loop binding protein (SLBP) binds the 3' end of histone mRNA and is present both in nucleus, and in the cytoplasm on the polyribosomes. SLBP participates in the processing of the histone pre-mRNA and in translation of the mature message. Histone mRNAs are rapidly degraded when cells are treated with inhibitors of DNA replication and are stabilized by inhibitors of translation, resulting in an increase in histone mRNA levels. Here, we show that SLBP is a component of the histone messenger ribonucleoprotein particle (mRNP). Histone mRNA from polyribosomes is immunoprecipitated with anti-SLBP. Most of the SLBP in cycloheximide-treated cells is present on polyribosomes as a result of continued synthesis and transport of the histone mRNP to the cytoplasm. When cells are treated with inhibitors of DNA replication, histone mRNAs are rapidly degraded but SLBP levels remain constant and SLBP is relocalized to the nucleus. SLBP remains active both in RNA binding and histone pre-mRNA processing when DNA replication is inhibited.
茎环结合蛋白(SLBP)结合组蛋白mRNA的3'末端,存在于细胞核以及多核糖体的细胞质中。SLBP参与组蛋白前体mRNA的加工以及成熟信使的翻译。当细胞用DNA复制抑制剂处理时,组蛋白mRNA会迅速降解,而用翻译抑制剂处理则会使其稳定,导致组蛋白mRNA水平升高。在此,我们表明SLBP是组蛋白信使核糖核蛋白颗粒(mRNP)的一个组成部分。来自多核糖体的组蛋白mRNA用抗SLBP抗体进行免疫沉淀。由于组蛋白mRNP持续合成并转运至细胞质,在环己酰亚胺处理的细胞中,大多数SLBP存在于多核糖体上。当细胞用DNA复制抑制剂处理时,组蛋白mRNA迅速降解,但SLBP水平保持恒定,且SLBP重新定位至细胞核。当DNA复制受到抑制时,SLBP在RNA结合和组蛋白前体mRNA加工方面均保持活性。