title: PYM binds the cytoplasmic exon-junction complex and ribosomes to enhance translation of spliced mRNAs.
abstract: Messenger RNAs produced by splicing are translated more efficiently than those produced from similar intronless precursor mRNAs (pre-mRNAs). The exon-junction complex (EJC) probably mediates this enhancement; however, the specific link between the EJC and the translation machinery has not been identified. The EJC proteins Y14 and magoh remain bound to spliced mRNAs after their export from the nucleus to the cytoplasm and are removed only when these mRNAs are translated. Here we show that PYM, a 29-kDa protein that binds the Y14-magoh complex in the cytoplasm, also binds, via a separate domain, to the small (40S) ribosomal subunit and the 48S preinitiation complex. Furthermore, PYM knockdown reduces the translation efficiency of a reporter protein produced from intron-containing, but not intronless, pre-mRNA. We suggest that PYM functions as a bridge between EJC-bearing spliced mRNAs and the translation machinery to enhance translation of the mRNAs.
authors.affiliation: Howard Hughes Medical Institute, Department of Biochemistry and Biophysics, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104-6148, USA.
authors.forename: Michael D
authors.initials: MD
authors.lastname: Diem
authors.forename: Chia C
authors.initials: CC
authors.lastname: Chan
authors.forename: Ihab
authors.initials: I
authors.lastname: Younis
authors.forename: Gideon
authors.initials: G
authors.lastname: Dreyfuss
mesh_terms: D002352:Carrier Proteins / Q000378:metabolism*; D002460:Cell Line; D003593:Cytoplasm / Q000378:metabolism*; D005091:Exons; D006801:Humans; D047468:Immunoprecipitation; D011485:Protein Binding; D014176:Protein Biosynthesis; D012326:RNA Splicing; D012333:RNA, Messenger / Q000235:genetics*; D012270:Ribosomes / Q000378:metabolism*
chemical_list: D002352:Carrier Proteins; C525835:PYM1 protein, human; D012333:RNA, Messenger