Lamond A I, Konarska M M, Grabowski P J, Sharp P A
Center for Cancer Research, Massachusetts Institute of Technology, Cambridge 02139.
Proc Natl Acad Sci U S A. 1988 Jan;85(2):411-5. doi: 10.1073/pnas.85.2.411.
Splicing complexes that form a rabbit beta-globin precursor mRNA (pre-mRNA) have been analyzed for their small nuclear RNA (snRNA) content by both affinity chromatography and specific probe hybridization of replicas of native electrophoretic gels. A pathway of spliceosome assembly was deduced that has at least three stages. (i) U2 small nuclear ribonucleoprotein (snRNP) alone binds to sequences of mRNA upstream of the 3' splice site. (ii) U4, U5, and U6 snRNPs bind, apparently simultaneously. (iii) U4 snRNP is released to generate a spliceosome that contains U2, U5, and U6 snRNPs together with the RNA intermediates in splicing. U1 snRNP was not detected in association with any of these complexes. A parallel analysis of the spliceosome found with an adenovirus precursor mRNA substrate yielded an identical snRNP composition with one additional, unidentified RNA species, called X. This latter RNA species was not detected in the spliceosome bound to the beta-globin substrate.
已通过亲和层析以及对天然电泳凝胶复制品进行特异性探针杂交，分析了形成兔β-珠蛋白前体mRNA（前体mRNA）的剪接复合物的小核RNA（snRNA）含量。由此推导出一个剪接体组装途径，该途径至少有三个阶段。（i）单独的U2小核核糖核蛋白（snRNP）与3'剪接位点上游的mRNA序列结合。（ii）U4、U5和U6 snRNP显然同时结合。（iii）U4 snRNP被释放，以生成一个剪接体，该剪接体包含U2、U5和U6 snRNP以及剪接过程中的RNA中间体。未检测到U1 snRNP与这些复合物中的任何一种相关联。对腺病毒前体mRNA底物的剪接体进行的平行分析产生了相同的snRNP组成，还有一种额外的未鉴定RNA物种，称为X。在与β-珠蛋白底物结合的剪接体中未检测到后一种RNA物种。
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