Belk J P, He F, Jacobson A
Department of Molecular Genetics and Microbiology, University of Massachusetts Medical School, Worcester 01655-0122, USA.
RNA. 1999 Aug;5(8):1055-70. doi: 10.1017/s1355838299990027.
The yeast NMD3 gene was identified in a two-hybrid screen using the nonsense-mediated mRNA decay factor, Upf1p, as bait. NMD3 was shown to encode an essential, highly conserved protein that associated principally with free 60S ribosomal subunits. Overexpression of a truncated form of Nmd3p, lacking 100 C-terminal amino acids and most of its Upf1p-interacting domain, had dominant-negative effects on both cell growth and protein synthesis and promoted the formation of polyribosome half-mers. These effects were eliminated by truncation of an additional 100 amino acids from Nmd3p. Overexpression of the nmd3delta100 allele also led to increased synthesis and destabilization of some ribosomal protein mRNAs, and increased synthesis and altered processing of 35S pre-rRNA. Our data suggest that Nmd3p has a role in the formation, function, or maintenance of the 60S ribosomal subunit and may provide a link for Upf1p to 80S monosomes.
酵母NMD3基因是在一个双杂交筛选中被鉴定出来的，该筛选以无义介导的mRNA降解因子Upf1p作为诱饵。NMD3被证明编码一种必需的、高度保守的蛋白质，该蛋白质主要与游离的60S核糖体亚基相关联。缺失100个C末端氨基酸及其大部分与Upf1p相互作用结构域的截短形式的Nmd3p的过表达，对细胞生长和蛋白质合成均具有显性负效应，并促进多核糖体半聚体的形成。从Nmd3p中再截短100个氨基酸可消除这些效应。nmd3delta100等位基因的过表达还导致一些核糖体蛋白mRNA的合成增加和稳定性降低，以及35S前体rRNA的合成增加和加工改变。我们的数据表明，Nmd3p在60S核糖体亚基的形成、功能或维持中发挥作用，并且可能为Upf1p与80S单体提供联系。
