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Title: A block in mammalian splicing occurring after formation of large complexes containing U1, U2, U4, U5, and U6 small nuclear ribonucleoproteins

Journal Article · · Molecular and Cellular Biology; (USA)
DOI:https://doi.org/10.1128/MCB.9.1.259· OSTI ID:5566526
; ;  [1]
  1. Memorial Sloan-Kettering Cancer Center, New York, NY (USA)

The assembly of mammalian pre-mRNAs into large 50S to 60S complexes, or spliceosomes, containing small nuclear ribonucleoproteins (snRNPs) leads to the production of splicing intermediates, 5' exon and lariat-3' exon, and the subsequent production of spliced products. Influenza virus NS1 asnd mRNA, which encodes a virus-specific protein, is spliced in infected cells to form another viral mRNA (the NS2 mRNA), such that the ratio of unspliced to spliced mRNA is 10 to 1. NS1 mRNA was not detectably spliced in vitro with nuclear extracts from uninfected HeLa cells. Surprisingly, despite the almost total absence of splicing intermediates in the in vitro reaction, NS1 mRNA very efficiently formed ATP-dependent 55S complexes. The formation of 55S complexes with NS1 mRNA was compared with that obtained with an adenovirus pre-mRNA (pKT1 transcript) by using partially purified splicing fractions that restricted the splicing of the pKT1 transcript to the production of splicing intermediates. On the basis of their results, the authors suggest mechanisms by which the splicing of NS1 mRNA is controlled in infected cells.

OSTI ID:
5566526
Journal Information:
Molecular and Cellular Biology; (USA), Vol. 9:1; ISSN 0270-7306
Country of Publication:
United States
Language:
English