Characterization of nuclear polyadenylated RNA-binding proteins in Saccharomyces cerevisiae.

Academic Article


  • To study the functions of heterogeneous nuclear ribonucleoproteins (hnRNPs), we have characterized nuclear polyadenylated RNA-binding (Nab) proteins from Saccharomyces cerevisiae. Nab1p, Nab2p, and Nab3p were isolated by a method which uses UV light to cross-link proteins directly bound to poly(A)+ RNA in vivo. We have previously characterized Nab2p, and demonstrated that it is structurally related to human hnRNPs. Here we report that Nab1p is identical to the Np13p/Nop3p protein recently implicated in both nucleocytoplasmic protein shuttling and pre-rRNA processing, and characterize a new nuclear polyadenylated RNA-binding protein, Nab3p. The intranuclear distributions of the Nab proteins were analyzed by three-dimensional immunofluorescence optical microscopy. All three Nab proteins are predominantly localized within the nucleoplasm in a pattern similar to the distribution of hnRNPs in human cells. The NAB3 gene is essential for cell viability and encodes an acidic ribonucleoprotein. Loss of Nab3p by growth of a GAL::nab3 mutant strain in glucose results in a decrease in the amount of mature ACT1, CYH2, and TPI1 mRNAs, a concomitant accumulation of unspliced ACT1 pre-mRNA, and an increase in the ratio of unspliced CYH2 pre-mRNA to mRNA. These results suggest that the Nab proteins may be required for packaging pre-mRNAs into ribonucleoprotein structures amenable to efficient nuclear RNA processing.
  • Keywords

  • Amino Acid Sequence, Base Sequence, Cell Division, Cell Nucleus, Cell Survival, Fungal Proteins, Genes, Fungal, Heterogeneous-Nuclear Ribonucleoproteins, Molecular Sequence Data, Nuclear Proteins, Nucleocytoplasmic Transport Proteins, RNA Precursors, RNA Processing, Post-Transcriptional, RNA, Fungal, RNA, Heterogeneous Nuclear, RNA, Messenger, RNA-Binding Proteins, Ribonucleoproteins, Saccharomyces cerevisiae, Saccharomyces cerevisiae Proteins
  • Digital Object Identifier (doi)

    Author List

  • Wilson SM; Datar KV; Paddy MR; Swedlow JR; Swanson MS
  • Start Page

  • 1173
  • End Page

  • 1184
  • Volume

  • 127
  • Issue

  • 5