期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1989
卷号：86
期号：17
页码：6523-6527
DOI：10.1073/pnas.86.17.6523
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：U3 small nuclear RNA is hydrogen-bonded to high molecular weight nucleolar RNA and can be isolated from greater than 60S pre-ribosomal ribonucleoprotein particles, suggesting that it is involved in processing of ribosomal RNA precursors (pre-rRNA) or in ribosome biogenesis. Here we have used in vivo psoralen cross-linking to identify the region of pre-rRNA interacting with U3 RNA. Quantitative hybridization selection/depletion experiments with clones of rRNA-encoding DNA (rDNA) and cross-linked nuclear RNA showed that all of the cross-linked U3 RNA was associated with a region that includes the external transcribed spacer (ETS) at the 5' end of the human rRNA precursor. To further identify the site of interaction within the approximately 3.7-kilobase ETS, Southern blots of rDNA clones were sandwich-hybridized with cross-linked RNA and then probed for cross-linked U3 RNA. These experiments showed that U3 RNA was cross-linked to a 258-base sequence between nucleotides +438 and +695, just downstream of the ETS early cleavage site (+414). The localization of U3 to this region of the rRNA precursor was not expected from previous models for a base-paired U3-rRNA interaction and suggests that U3 plays a role in the initial pre-rRNA processing event.
