Wu R S, Kumar A, Warner J R
Proc Natl Acad Sci U S A. 1971 Dec;68(12):3009-14. doi: 10.1073/pnas.68.12.3009.
A new drug, camptothecin, has been used to study the regulation of ribosome synthesis in HeLa cells. 5 muM camptothecin inhibits the synthesis of heterogeneously sedimenting nuclear RNA by about 70%. Camptothecin also blocks a specific step in the processing of ribosomal precursor RNA, allowing the conversion of 45S RNA to 32S RNA, but inhibiting the conversion of 32S RNA to 28S RNA. The action of camptothecin, unlike that of actinomycin D, is rapidly reversible. Within 5 min after the removal of the drug, ribosomal precursor RNA synthesis and maturation resume at the normal rate. Ribosomal proteins made in the presence of camptothecin do not accumulate in the nucleolus, and are not subsequently used to form ribosomes if RNA synthesis is allowed to resume.
一种新药喜树碱已被用于研究HeLa细胞中核糖体合成的调控。5微摩尔的喜树碱可抑制不均一沉降核RNA的合成约70%。喜树碱还阻断核糖体前体RNA加工过程中的一个特定步骤，允许45S RNA转化为32S RNA，但抑制32S RNA转化为28S RNA。与放线菌素D不同，喜树碱的作用是快速可逆的。去除药物后5分钟内，核糖体前体RNA的合成和成熟恢复正常速率。在喜树碱存在的情况下合成的核糖体蛋白不会在核仁中积累，如果允许RNA合成恢复，这些蛋白随后也不会用于形成核糖体。
