Human pre-mRNA cleavage factor II(m) contains homologs of yeast proteins and bridges two other cleavage factors.
Six different protein factors are required in vitro for 3' end formation of mammalian pre-mRNAs by endonucleolytic cleavage and polyadenylation. Five of the factors have been purified and most of their components cloned, but cleavage factor II(m) (CF II(m)) remained uncharacterized. We have purified CF II(m) from HeLa cell nuclear extract by several chromatographic steps. During purification, CF II(m) activity separated into two components, one essential (CF IIA(m)) and one stimulatory (CF IIB(m)) for the cleavage reaction. CF IIA(m) fractions contain the human homologs of two yeast 3' end processing factors, Pcf11p and Clp1p, as well as cleavage factor I(m) (CF I(m)) and several splicing and transcription factors. We report the cloning of hClp1 and show that it is a genuine subunit of CF IIA(m). Antibodies directed against hClp1 deplete cleavage activity, but not polyadenylation activity from HeLa cell nuclear extract. hClp1 interacts with CF I(m) and the cleavage and polyadenylation specificity factor CPSF, suggesting that it bridges these two 3' end processing factors within the cleavage complex.
de Vries
H
H
Department of Cell Biology, Biozentrum, University of Basel, Klingelbergstrasse 70, CH-4056 Basel, Germany.
Rüegsegger
U
U
Hübner
W
W
Friedlein
A
A
Langen
H
H
Keller
W
W
D000595:Amino Acid Sequence; D001483:Base Sequence; D017124:Conserved Sequence; D017931:DNA Primers / Q000235:genetics; D019143:Evolution, Molecular; D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics; D006367:HeLa Cells; D006801:Humans; D008969:Molecular Sequence Data; D021122:Protein Subunits; D012322:RNA Precursors / Q000378:metabolism*; D012323:RNA Processing, Post-Transcriptional; D012326:RNA Splicing; D012331:RNA, Fungal / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D014158:Transcription, Genetic; D039221:mRNA Cleavage and Polyadenylation Factors
D017931:DNA Primers; D005656:Fungal Proteins; D021122:Protein Subunits; D012322:RNA Precursors; D012331:RNA, Fungal; D016601:RNA-Binding Proteins; D039221:mRNA Cleavage and Polyadenylation Factors