在酵母细胞内，每一秒就有2000多个核糖体被合成。核糖体蛋白的快速合成，高效的运送到细胞核，并正确的组装成核糖体亚基，对酵母能够快速生长是必须的。
近日，来自奥地利格拉茨大学的研究人员Brigitte Pertschy等人发现，锚蛋白重复蛋白Yar1能够保护核糖体蛋白Rps3免于积聚。相关论文发表在5月8日的The Journal of Biological Chemistry。
Yar1能直接与核糖体小亚基蛋白Rps3相互作用。它伴随着新和成的Rps3从细胞质运送到细胞核，在细胞核内Rps3被组装成核糖体亚基前体。
研究发现，yar1缺失菌株表现出与rps3突变株相似的表型，这表明20S前体rRNA出现累积，40SrRNA输出发生缺陷。
rps3突变与yar1缺失的组合增强了这些表型，而RPS3的增强表达则会抑制yar1缺失株表现出缺陷特征。
进一步研究表明，在体外，Yar1能够保护Rps3免于积聚；在体内，则能够增加Rps3的可溶性。
Brigitte Pertschy表示，Yar1是Rps3特异性的分子伴侣，能够保持Rps3的可溶性直到它组装为核糖体前体。该研究表明了核糖体蛋白需要保护免于积聚的一种机制。（生物谷Deepblue编译）
doi: 10.1074/jbc.M112.365791
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Yar1 protects the ribosomal protein Rps3 from aggregation
Barbara Koch, Valentin Mitterer, Johannes Niederhauser, Tamsyn Stanborough, Guillaume Murat, Gerald Rechberger, Helmut Bergler, Dieter Kressler and Brigitte Pertschy.
2000 ribosomes have to be synthesized in yeast every minute. Therefore the fast production of ribosomal proteins, their efficient delivery to the nucleus and correct incorporation into ribosomal subunits are prerequisites for optimal growth rates.Here, we report that the ankyrin repeat protein Yar1 directly interacts with the small ribosomal subunit protein Rps3 and accompanies newly synthesized Rps3 from the cytoplasm into the nucleus where Rps3 is assembled into pre-ribosomal subunits.A yar1 deletion strain displays a similar phenotype as an rps3 mutant strain, showing an accumulation of 20S pre-rRNA and a 40S export defect.The combination of an rps3 mutation with a yar1 deletion leads to an enhancement of these phenotypes, while increased expression of RPS3 suppresses the defects of a yar1 deletion strain.We further show that Yar1 protects Rps3 from aggregation in vitro and increases its solubility in vivo.Our data suggest that Yar1 is a specific chaperone for Rps3, which serves to keep Rps3 soluble until its incorporation into the pre-ribosome.
