Demianova M, Formosa T G, Ellis S R
Department of Biochemistry, University of Louisville, Kentucky 40292, USA.
J Biol Chem. 1996 May 10;271(19):11383-91. doi: 10.1074/jbc.271.19.11383.
We report here the isolation of two genes from the yeast, Saccharomyces cerevisiae, that encode proteins closely related to mammalian p40/laminin receptor precursors (LRPs). The yeast genes, designated YST1 and YST2, encode proteins with over 95% amino acid sequence identity with one another and over 60% identity with the human p40/laminin receptor precursor. The Yst/p40/37-LRP proteins are also more distantly related to the S2 family of ribosomal proteins. Analysis of the distribution of Yst1 tagged with the c-myc epitope revealed that the Yst proteins are components of the 40 S ribosomal subunit. Disruption of either YST1 or YST2 causes a significant reduction in growth rate, while disruption of both genes is lethal. Compared to wild type, polysome profiles in strains lacking either YST1 or YST2 show a pronounced shift from larger to smaller polysomes. This shift is accompanied by a substantial increase in free 60 S subunits and reduced levels of 40 S subunits. We conclude that the Yst proteins are required for translation and contribute to the assembly and/or stability of the 40 S ribosomal subunit.
我们在此报告从酿酒酵母中分离出两个基因，它们编码的蛋白质与哺乳动物p40/层粘连蛋白受体前体（LRP）密切相关。这两个酵母基因，命名为YST1和YST2，编码的蛋白质彼此间氨基酸序列同一性超过95%，与人p40/层粘连蛋白受体前体的同一性超过60%。Yst/p40/37-LRP蛋白与核糖体蛋白的S2家族也有较远的亲缘关系。对用c-myc表位标记的Yst1分布的分析表明，Yst蛋白是40 S核糖体亚基的组成成分。破坏YST1或YST2都会导致生长速率显著降低，而同时破坏这两个基因则是致死的。与野生型相比，缺乏YST1或YST2的菌株中的多核糖体图谱显示出从较大多核糖体向较小多核糖体的明显转变。这种转变伴随着游离60 S亚基的大量增加和40 S亚基水平的降低。我们得出结论，Yst蛋白是翻译所必需的，并有助于40 S核糖体亚基的组装和/或稳定性。
