title: RNA annealing activity is intrinsically associated with U2AF.
abstract: U2AF is a protein that is essential for the formation of the prespliceosome complex during pre-mRNA splicing. It contains two subunits, 65 and 35 kDa, although only the 65-kDa subunit has been shown to be essential for its splicing activity. Here, we show that the 65-kDa subunit mediates the annealing of complementary single-stranded RNAs or single-stranded DNAs. This activity was shown to reverse the action of RNA helicase A, an enzyme that catalyzes the displacement of duplex RNAs. The NH2-terminal region of the 65-kDa subunit of U2AF, containing arginine-serine (RS) dipeptides and basic amino acid sequences, was shown to be essential for the annealing of complementary sequences, RNA binding, and the inhibition of RNA helicase A activity. Thus, through the combined action of U2AF and RNA helicases, duplex RNA regions can be reversibly formed and displaced. Such reactions appear to be critical for pre-mRNA splicing, translation, and transcription.
authors.affiliation: Graduate Program in Molecular Biology, Memorial Sloan-Kettering Cancer Center, Sloan-Kettering Institute, New York, New York 10021.
authors.forename: C G
authors.initials: CG
authors.lastname: Lee
authors.forename: P D
authors.initials: PD
authors.lastname: Zamore
authors.forename: M R
authors.initials: MR
authors.lastname: Green
authors.forename: J
authors.initials: J
authors.lastname: Hurwitz
mesh_terms: D001483:Base Sequence; D004247:DNA / Q000378:metabolism; D006147:Guanine / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D008969:Molecular Sequence Data; D009687:Nuclear Proteins; D012313:RNA / Q000235:genetics / Q000378:metabolism*; D020365:RNA Helicases; D012316:RNA Nucleotidyltransferases / Q000037:antagonists & inhibitors; D012326:RNA Splicing; D012261:Ribonucleoproteins / Q000378:metabolism*; D000072668:Splicing Factor U2AF
chemical_list: D009687:Nuclear Proteins; D012261:Ribonucleoproteins; D000072668:Splicing Factor U2AF; C000607494:U2AF2 protein, human; D006147:Guanine; D012313:RNA; D004247:DNA; D012316:RNA Nucleotidyltransferases; D020365:RNA Helicases