High impact information on NAB2

• Depletion of Kap104p resulted in a rapid shift of Nab2p from the nucleus to the cytoplasm without affecting the localization of other nuclear proteins tested [1].
• The protein bound directly to repeat-containing nucleoporins and to a cytosolic pool of two nuclear messenger RNA (mRNA) binding proteins, Nab2p and Nab4p [1].
• We propose that Nab2p and Yra1p are required for proper mRNP docking to the Mlp platform [2].
• Here, we identify Nab2p as a nuclear poly(A)-binding protein required for both poly(A) tail length control and nuclear export of mRNA [3].
• Dual requirement for yeast hnRNP Nab2p in mRNA poly(A) tail length control and nuclear export [3].

Biological context of NAB2

• NAB2: a yeast nuclear polyadenylated RNA-binding protein essential for cell viability [4].
• NAB2 is located on chromosome VII within a cluster of ribonucleoprotein genes, and its expression is essential for cell growth [4].
• We propose that Nab2p provides an important link between the termination of mRNA polyadenylation and nuclear export [3].
• Identification and functional characterization of a novel nuclear localization signal present in the yeast Nab2 poly(A)+ RNA binding protein [5].
• In an exhaustive screen of the S. cerevisiae genome, the most frequently selected open reading frame was the nuclear mRNA-binding protein, Nab2p [6].

Anatomical context of NAB2

• Using an in vitro nuclear import assay, we demonstrate that Kap104p can direct the import into isolated human cell nuclei of a substrate containing a wild-type, but not a defective mutant, Nab2p NLS [5].

Associations of NAB2 with chemical compounds

• Our experiments demonstrate that arginine methylation is required for the export of Nab2p from the nucleus and therefore establish an in vivo effect of this modification [7].
• The Nab2 protein consists of the following four domains: a unique N-terminal domain, a glutamine-rich domain, an arginine-glycine (RGG) domain, and a zinc finger domain [8].

Physical interactions of NAB2

• Here, we define a Nab2p sequence that binds to Kap104p and that functions as an NLS in both human and yeast cells despite lacking any evident similarity to basic or M9 NLSs [5].
• This N-terminal Nab2 domain is distinct from its RNA binding domains suggesting Nab2 could bind Gfd1 and RNA simultaneously [9].

Regulatory relationships of NAB2

• Nab2p is required for poly(A) RNA export in Saccharomyces cerevisiae and is regulated by arginine methylation via Hmt1p [7].

Other interactions of NAB2

• 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 [10].
• Also, addition of Kap104p to Nab2p and Nab4p/Hrp1p prebound to single-stranded DNA-cellulose stimulated release of both proteins from the resin [11].
• Supporting the hypothesis that these proteins display transcript specificity, we identified a unique 7-nucleotide sequence overrepresented in the transcripts highly associated with Nab2 and Nab4/Hrp1 using the REDUCE algorithm [12].
• 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 [13].
• A Nab2-Gfd1 complex was also identified by coimmunoprecipitation from yeast lysates [9].

Analytical, diagnostic and therapeutic context of NAB2

• Cellular immunofluorescence, using both monoclonal and polyclonal antibodies, demonstrates that the NAB2 protein is localized within the nucleus [4].

References