Hannon G J, Maroney P A, Nilsen T W
Department of Molecular Biology and Microbiology, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106-4960.
J Biol Chem. 1991 Dec 5;266(34):22792-5.
In nematodes, a fraction of mRNAs acquires a common 22-nucleotide 5'-terminal spliced leader sequence via a trans-splicing reaction. The same premessenger RNAs which receive the spliced leader are also processed by conventional cis-splicing. Whole cell extracts prepared from synchronous embryos of the parasitic nematode Ascaris lumbricoides catalyze both cis- and trans-splicing. We have used this cell-free system and oligodeoxynucleotide directed RNase H digestion to assess the U small nuclear RNA requirements for nematode cis- and trans-splicing. These experiments indicated that both cis- and trans-splicing require intact U2 and U4/U6 small nuclear ribonucleoproteins (snRNPs). However, whereas cis-splicing displays the expected requirement for an intact U1 snRNP, trans-splicing is unaffected when approximately 90% of U1 snRNP is degraded. These results suggest that 5' splice site identification differs in nematode cis- and trans-splicing.
在线虫中，一部分mRNA通过反式剪接反应获得一个共同的22个核苷酸的5'末端剪接前导序列。接受剪接前导序列的相同前体信使RNA也通过传统的顺式剪接进行加工。从寄生线虫蛔虫同步胚胎制备的全细胞提取物催化顺式和反式剪接。我们使用这个无细胞系统和寡脱氧核苷酸定向RNase H消化来评估线虫顺式和反式剪接对U小核RNA的需求。这些实验表明，顺式和反式剪接都需要完整的U2和U4/U6小核核糖核蛋白（snRNP）。然而，虽然顺式剪接显示出对完整U1 snRNP的预期需求，但当大约90%的U1 snRNP被降解时，反式剪接不受影响。这些结果表明，线虫顺式和反式剪接中5'剪接位点的识别有所不同。
