Strub K, Galli G, Busslinger M, Birnstiel M L
EMBO J. 1984 Dec 1;3(12):2801-7. doi: 10.1002/j.1460-2075.1984.tb02212.x.
3' Processing of sea urchin H3 histone pre-mRNA depends on a small nuclear RNP which contains an RNA of nominally 60 nucleotide length, referred to below as U7 RNA. The U7 RNA can be enriched by precipitation of sea urchin U-snRNPs with human systematic lupus erythematosus antiserum of the Sm serotype. We have prepared cDNA clones of U7 RNA and determined by hybridization techniques that this RNA is present in sea urchin eggs at 30-fold lower molar concentration than U1 RNA. The RNA sequences derived from an analysis of eight U7 cDNA clones show neither homologies nor complementarities to any other know U-RNAs. The 3' portion of the presumptive RNA sequence can be folded into a stem-loop structure. The 5'-terminal sequences would be largely unstructured as free RNA. Their most striking feature is their base complementarity to the 3' conserved sequences of histone pre-mRNAs. Six out of nine bases of the conserved CAAGAAAGA sequence of the histone mRNA precursor and 13 out of 16 nucleotides from the conserved palindrome can be base paired with presumptive U7 RNA sequence, suggesting a unique hybrid structure for a processing intermediate formed from histone precursor and U7 RNA.
海胆H3组蛋白前体mRNA的3'端加工依赖于一种小核核糖核蛋白，该蛋白含有一种名义长度为60个核苷酸的RNA，以下称为U7 RNA。通过用人系统性红斑狼疮Sm血清型抗血清沉淀海胆U - snRNP，可以富集U7 RNA。我们制备了U7 RNA的cDNA克隆，并通过杂交技术确定，这种RNA在海胆卵中的摩尔浓度比U1 RNA低30倍。对八个U7 cDNA克隆进行分析得到的RNA序列，与任何其他已知的U - RNA既无同源性也无互补性。推测的RNA序列的3'部分可以折叠成茎环结构。5'端序列作为游离RNA时基本上是无结构的。它们最显著的特征是与组蛋白前体mRNA的3'保守序列具有碱基互补性。组蛋白mRNA前体保守的CAAGAAAGA序列的九个碱基中有六个，以及保守回文序列的16个核苷酸中有13个，可以与推测的U7 RNA序列碱基配对，这表明由组蛋白前体和U7 RNA形成的加工中间体具有独特的杂交结构。
