title: A pre-mRNA-binding protein accompanies the RNA from the gene through the nuclear pores and into polysomes.
abstract: In the larval salivary glands of C. tentans, it is possible to visualize by electron microscopy how Balbiani ring (BR) pre-mRNA associates with proteins to form pre-mRNP particles, how these particles move to and through the nuclear pore, and how the BR RNA is engaged in the formation of giant polysomes in the cytoplasm. Here, we study C. tentans hrp36, an abundant protein in the BR particles, and establish that it is similar to the mammalian hnRNP A1. By immuno-electron microscopy it is demonstrated that hrp36 is added to BR RNA concomitant with transcription, remains in nucleoplasmic BR particles, and is translocated through the nuclear pore still associated with BR RNA. It appears in the giant BR RNA-containing polysomes, where it remains as an abundant protein in spite of ongoing translation.
authors.affiliation: Department of Cell and Molecular Biology, Medical Nobel Institute, Karolinska Institutet, Stockholm, Sweden.
authors.forename: N
authors.initials: N
authors.lastname: Visa
authors.forename: A T
authors.initials: AT
authors.lastname: Alzhanova-Ericsson
authors.forename: X
authors.initials: X
authors.lastname: Sun
authors.forename: E
authors.initials: E
authors.lastname: Kiseleva
authors.forename: B
authors.initials: B
authors.lastname: Björkroth
authors.forename: T
authors.initials: T
authors.lastname: Wurtz
authors.forename: B
authors.initials: B
authors.lastname: Daneholt
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001692:Biological Transport; D002467:Cell Nucleus / Q000737:chemistry; D002683:Chironomidae; D003001:Cloning, Molecular; D003593:Cytoplasm / Q000737:chemistry; D017344:Genes, Insect / Q000235:genetics; D000076245:Heterogeneous Nuclear Ribonucleoprotein A1; D034481:Heterogeneous-Nuclear Ribonucleoprotein Group A-B; D034441:Heterogeneous-Nuclear Ribonucleoproteins; D008969:Molecular Sequence Data; D009685:Nuclear Envelope / Q000737:chemistry / Q000378:metabolism*; D011132:Polyribosomes / Q000737:chemistry / Q000378:metabolism*; D012322:RNA Precursors / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000032:analysis / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D012261:Ribonucleoproteins / Q000032:analysis / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D012469:Salivary Glands / Q000737:chemistry; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid
chemical_list: D000076245:Heterogeneous Nuclear Ribonucleoprotein A1; D034481:Heterogeneous-Nuclear Ribonucleoprotein Group A-B; D034441:Heterogeneous-Nuclear Ribonucleoproteins; D012322:RNA Precursors; D016601:RNA-Binding Proteins; D012261:Ribonucleoproteins