Abstract
Endonucleolytic cleavage of pre-mRNAs is the first step during eukaryotic mRNA 3' end formation. It has been proposed that cleavage factors CF IA, CF IB and CF II are required for pre-mRNA 3' end cleavage in yeast. CF IB is composed of a single polypeptide, Nab4p/Hrp1p, which is related to the A/B group of metazoan heterogeneous nuclear ribonucleoproteins (hnRNPs) that function as antagonistic regulators of 5' splice site selection. Here, we provide evidence that Nab4p/Hrp1p is not required for pre-mRNA 3' end endonucleolytic cleavage. We show that CF IA and CF II devoid of Nab4p/Hrp1p are sufficient to cleave a variety of RNA substrates but that cleavage occurs at multiple sites. Addition of Nab4p/Hrp1p prevents these alternative cleavages in a concentration-dependent manner, suggesting an essential and conserved role for some hnRNPs in pre-mRNA cleavage site selection.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Base Sequence
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Cytochrome c Group / biosynthesis
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Cytochrome c Group / genetics
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Cytochromes c*
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Heterogeneous-Nuclear Ribonucleoproteins
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Models, Genetic
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Molecular Sequence Data
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Poly A / metabolism
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RNA Precursors / metabolism*
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RNA Processing, Post-Transcriptional*
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RNA, Fungal / metabolism*
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RNA, Messenger / biosynthesis*
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RNA-Binding Proteins / metabolism
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Ribonucleoproteins / metabolism*
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Saccharomyces cerevisiae
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Saccharomyces cerevisiae Proteins*
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Substrate Specificity
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mRNA Cleavage and Polyadenylation Factors
Substances
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CYC1 protein, S cerevisiae
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Cytochrome c Group
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Heterogeneous-Nuclear Ribonucleoproteins
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RNA Precursors
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RNA, Fungal
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RNA, Messenger
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RNA-Binding Proteins
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Ribonucleoproteins
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Saccharomyces cerevisiae Proteins
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mRNA Cleavage and Polyadenylation Factors
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Poly A
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Cytochromes c