Tarn W Y, Steitz J A
Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, Howard Hughes Medical Institute, New Haven, CT 06536-0812, USA.
Science. 1996 Sep 27;273(5283):1824-32. doi: 10.1126/science.273.5283.1824.
Removal of a rare class of metazoan precursor messenger RNA introns with AU-AC at their termini is catalyzed by a spliceosome that contains U11, U12, and U5 small nuclear ribonucleoproteins. Two previously unidentified, low-abundance human small nuclear RNAs (snRNAs), U4atac and U6atac, were characterized as associated with the AT-AC spliceosome and necessary for AT-AC intron splicing. The excision of AT-AC introns therefore requires four snRNAs not found in the major spliceosome. With the use of psoralen crosslinking, a U6atac interaction with U12 was identified that is similar to a U6-U2 helix believed to contribute to the spliceosomal active center. The conservation of only limited U6atac sequences in the neighborhood of this interaction and the potential of U6atac to base pair with the 5' splice site consensus for AT-AC introns provide support for current models of the core of the spliceosome.
一类罕见的后生动物前体信使核糖核酸内含子，其末端为AU-AC，由一个包含U11、U12和U5小核核糖核蛋白的剪接体催化去除。两种先前未鉴定的低丰度人类小核RNA（snRNA），即U4atac和U6atac，被鉴定为与AT-AC剪接体相关，并且是AT-AC内含子剪接所必需的。因此，AT-AC内含子的切除需要四种在主要剪接体中未发现的snRNA。通过补骨脂素交联，鉴定出U6atac与U12的相互作用，该相互作用类似于一种被认为有助于剪接体活性中心的U6-U2螺旋。在这种相互作用附近仅有限的U6atac序列的保守性以及U6atac与AT-AC内含子5'剪接位点共有序列碱基配对的可能性，为当前剪接体核心模型提供了支持。
