The C-terminal domain of myosin-like protein 1 (Mlp1p) is a docking site for heterogeneous nuclear ribonucleoproteins that are required for mRNA export.
For mRNA to be transported from the nucleus to the cytoplasm, it must travel from the site of transcription through the nuclear interior to the nuclear pore. Studies in Saccharomyces cerevisiae have suggested a relationship between poly(A) RNA trafficking and myosin-like protein 1 (Mlp1p), a nuclear-pore associated protein that is homologous to the mammalian Tpr (translocated promoter region) protein [Kosova, B., Panté, N., Rollenhagen, C., Podtelejnikov, A., Mann, M., Aebi, U., and Hurt, E. (2000) J. Biol. Chem. 275, 343-350]. We identified a yeast two-hybrid interaction between the C-terminal globular domain of Mlp1p and Nab2p, a shuttling heterogeneous nuclear ribonucleoprotein that is required for mRNA export. Coimmunoprecipitation confirms that Nab2p also interacts with full-length Mlp1p and in vitro binding experiments show that Nab2p binds directly to the C-terminal domain of Mlp1p. In addition, our experiments reveal that the C-terminal domain of Mlp1p is both necessary and sufficient to cause accumulation of poly(A) RNA and Nab2p in the nucleus. We propose a model where Mlp1p acts as a checkpoint at the nuclear pore by interacting with export-competent ribonucleoprotein complexes through its C-terminal globular domain. This study identifies Nab2p as a heterogeneous nuclear ribonucleoprotein found in complex with Mlp1p and begins to delineate the path that mRNA travels from the chromatin to the nuclear pore.
Green
Deanna M
DM
Department of Biochemistry, Emory University School of Medicine, Atlanta, GA 30322, USA.
Johnson
Christie P
CP
Hagan
Henry
H
Corbett
Anita H
AH
D002455:Cell Division; D002467:Cell Nucleus / Q000378:metabolism; D005690:Galactose / Q000378:metabolism; D005822:Genetic Vectors; D005947:Glucose / Q000378:metabolism; D005982:Glutathione Transferase / Q000378:metabolism; D049452:Green Fluorescent Proteins; D017404:In Situ Hybridization, Fluorescence; D008164:Luminescent Proteins / Q000378:metabolism; D008565:Membrane Proteins / Q000737:chemistry*; D022022:Nuclear Pore; D028861:Nuclear Pore Complex Proteins; D009687:Nuclear Proteins; D029543:Nucleocytoplasmic Transport Proteins / Q000737:chemistry / Q000378:metabolism; D011061:Poly A / Q000378:metabolism; D011233:Precipitin Tests; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000737:chemistry / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000378:metabolism; D020798:Two-Hybrid System Techniques
D008164:Luminescent Proteins; C080988:MLP1 protein, S cerevisiae; D008565:Membrane Proteins; C080773:NAB2 protein, S cerevisiae; D028861:Nuclear Pore Complex Proteins; D009687:Nuclear Proteins; D029543:Nucleocytoplasmic Transport Proteins; D011518:Proto-Oncogene Proteins; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D029701:Saccharomyces cerevisiae Proteins; C073597:TPR protein, human; D049452:Green Fluorescent Proteins; D011061:Poly A; D005982:Glutathione Transferase; D005947:Glucose; D005690:Galactose