title: Intranuclear binding in space and time of exon junction complex and NXF1 to premRNPs/mRNPs in vivo.
abstract: Eukaryotic gene expression requires the ordered association of numerous factors with precursor messenger RNAs (premRNAs)/messenger RNAs (mRNAs) to achieve efficiency and regulation. Here, we use the Balbiani ring (BR) genes to demonstrate the temporal and spatial association of the exon junction complex (EJC) core with gene-specific endogenous premRNAs and mRNAs. The EJC core components bind cotranscriptionally to BR premRNAs during or very rapidly after splicing. The EJC core does not recruit the nonsense-mediated decay mediaters UPF2 and UPF3 until the BR messenger RNA protein complexes (mRNPs) enter the interchromatin. Even though several known adapters for the export factor NXF1 become part of BR mRNPs already at the gene, NXF1 binds to BR mRNPs only in the interchromatin. In steady state, a subset of the BR mRNPs in the interchromatin binds NXF1, UPF2, and UPF3. This binding appears to occur stochastically, and the efficiency approximately equals synthesis and export of the BR mRNPs. Our data provide unique in vivo information on how export competent eukaryotic mRNPs are formed.
authors.affiliation: Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, SE-106 91 Stockholm, Sweden.
authors.forename: Petra
authors.initials: P
authors.lastname: Björk
authors.affiliation: Department of Mathematics, Stockholm University, SE-106 91 Stockholm, Sweden.
authors.forename: Jan-Olov
authors.initials: JO
authors.lastname: Persson
authors.affiliation: Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, SE-106 91 Stockholm, Sweden Lars.Wieslander@su.se.
authors.forename: Lars
authors.initials: L
authors.lastname: Wieslander
mesh_terms: D000818:Animals; D002467:Cell Nucleus / Q000378:metabolism; D002683:Chironomidae; D039601:Eukaryotic Initiation Factor-4A / Q000378:metabolism; D005091:Exons; D019476:Insect Proteins / Q000378:metabolism*; D009687:Nuclear Proteins / Q000378:metabolism*; D011485:Protein Binding; D055503:Protein Multimerization; D011498:Protein Precursors / Q000378:metabolism*; D021381:Protein Transport; D012333:RNA, Messenger / Q000378:metabolism; D012261:Ribonucleoproteins / Q000378:metabolism*
chemical_list: D019476:Insect Proteins; D009687:Nuclear Proteins; D011498:Protein Precursors; D012333:RNA, Messenger; D012261:Ribonucleoproteins; C026452:messenger ribonucleoprotein; D039601:Eukaryotic Initiation Factor-4A