Nika J, Erickson F L, Hannig E M
Department of Molecular and Cell Biology, University of Texas at Dallas, Richardson 75083-0688, USA.
Yeast. 1997 Sep 30;13(12):1155-66. doi: 10.1002/(SICI)1097-0061(19970930)13:12<1155::AID-YEA166>3.0.CO;2-O.
Genes encoding members of the highly conserved QM family have been identified in eukaryotic organisms from yeast to man. Results of previous studies have suggested roles for QM in control of cell growth and proliferation, perhaps as a tumor suppressor, and in energy metabolism. We identified recessive lethal alleles of the Saccharomyces cerevisiae QM homolog GRC5 that increased GCN4 expression when present in multiple copies. These alleles encode truncated forms of the yeast QM protein Grc5p. Using a functional epitope-tagged GRC5 allele, we localized Grc5p to a 60S fraction that contained the large ribosomal subunit. Two-dimensional gel analysis of highly purified yeast ribosomes indicated that Grc5p corresponds to 60S ribosomal protein L9. This identification is consistent with the predicted physical characteristics of eukaryotic QM proteins, the highly biased codon usage of GRC5, and the presence of putative Rap1p-binding sites in the 5' sequences of the yeast GRC5 gene.
从酵母到人类的真核生物中已鉴定出编码高度保守的QM家族成员的基因。先前的研究结果表明，QM在控制细胞生长和增殖（可能作为一种肿瘤抑制因子）以及能量代谢中发挥作用。我们鉴定出酿酒酵母QM同源物GRC5的隐性致死等位基因，当这些等位基因以多拷贝形式存在时会增加GCN4的表达。这些等位基因编码酵母QM蛋白Grc5p的截短形式。使用带有功能性表位标签的GRC5等位基因，我们将Grc5p定位到一个包含大核糖体亚基的60S组分中。对高度纯化的酵母核糖体进行二维凝胶分析表明，Grc5p对应于60S核糖体蛋白L9。这一鉴定结果与真核QM蛋白的预测物理特性、GRC5高度偏向的密码子使用情况以及酵母GRC5基因5'序列中假定的Rap1p结合位点的存在相一致。
