High impact information on HRP1

• 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].
• Hmt1 methylates Yra1 and Hrp1, two mRNA-binding proteins important for mRNA processing and export [2].
• In contrast, the mRNA cap methyltransferase and the Hrp1/CFIB polyadenylation factor cross-link to both promoter and coding regions [3].
• The HRP1 gene was originally isolated as a suppressor of a temperature-sensitive npl3 allele, a gene encoding a protein involved in mRNA export [4].
• Using a genetic screen in S. pombe, we identified the CHD-Mi2 class chromatin remodeling ATPase, Hrp1, as a termination factor [5].

Biological context of HRP1

• We show that HRP1 is essential for cell growth and that the corresponding protein is located in the nucleus [6].
• Significantly, nab4 mutants showed a striking, desensitized growth phenotype when exposed to amino acid stress conditions suggesting a biological consequence to the associations we observed [7].
• Validating our approach, our bioinformatics analysis correctly identified the known binding site for Nab4/Hrp1 [7].
• Kap104p is a Saccharomyces cerevisiae nuclear import receptor for two essential mRNA-binding proteins, Nab2p and Nab4p/Hrp1p [8].
• Using immunoprecipitation techniques, the protein has been identified as Hrp1, a heteronuclear RNA binding protein [9].

Physical interactions of HRP1

• A mutation in HRP1 that stabilizes nonsense-containing mRNAs abolishes its affinity for the DSE and fails to interact with Upf1p [10].

Regulatory relationships of HRP1

• Mutations in HRP1 suppress all npl3 temperature-sensitive alleles but do not bypass an npl3 null allele [6].
• Here we describe the identification and characterization of the Hrp1/Nab4 protein as a DSE-binding factor that activates NMD [10].

Other interactions of HRP1

• The yeast hnRNP-like protein Hrp1/Nab4 marks a transcript for nonsense-mediated mRNA decay [10].
• The yeast hnRNP-like protein Hrp1/Nab4 sccumulates in the cytoplasm after hyperosmotic stress: a novel Fps1-dependent response [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 [7].
• We suggest a model in which these three factors and Ufd1p are part of a regulatory complex that exploits Pab1p to link cleavage and polyadenylation factors of CFIA and CFIB (cleavage factors IA and IB) to the polyadenylation factors of CPF (cleavage and polyadenylation factor) [12].
• Previous work demonstrated that the UV cross-linking of purified Hrp1 to RNA required the UA-rich element, but the contact point of Rna15 was not known [13].

References