Zarkower D, Wickens M
EMBO J. 1987 Jan;6(1):177-86. doi: 10.1002/j.1460-2075.1987.tb04736.x.
Formation of the 3' termini of mRNAs in animal cells involves endonucleolytic cleavage of a pre-mRNA, followed by polyadenylation of the newly formed end. Here we demonstrate that, during cleavage in vitro, the highly conserved AAUAAA sequence of the pre-mRNA forms a complex with a factor present in a crude nuclear extract. This complex is required for cleavage and polyadenylation. It normally is transient, but is very stable on cleaved RNA to which a single terminal cordycepin residue has been added. The complex can form either during the cleavage reaction, or on a synthetic RNA that ends at the polyadenylation site. Mutations which prevent cleavage also prevent complex formation. The complex dissociates during or after polyadenylation, enabling the released activities to catalyze a second round of cleavage.
动物细胞中mRNA 3'末端的形成涉及前体mRNA的内切核酸酶切割，随后是新形成末端的多聚腺苷酸化。在这里，我们证明，在体外切割过程中，前体mRNA高度保守的AAUAAA序列与粗核提取物中存在的一种因子形成复合物。这种复合物是切割和多聚腺苷酸化所必需的。它通常是短暂的，但在添加了单个末端虫草素残基的切割RNA上非常稳定。该复合物可以在切割反应过程中形成，也可以在多聚腺苷酸化位点结束的合成RNA上形成。阻止切割的突变也会阻止复合物的形成。该复合物在多聚腺苷酸化过程中或之后解离，使释放的活性能够催化第二轮切割。
