Disease relevance of MEX67

• This complex, either isolated from yeast or assembled in Escherichia coli, can bind in vitro to RNA through Mex67p [1].

High impact information on MEX67

• We identified the mRNAs that bind two conserved yeast mRNA export factors, Yra1 (refs. 1-5) and Mex67 (refs. 6,7), on a genome-wide scale and determined their level of binding [2].
• Yra1 and Mex67 bind approximately 1,000 and 1,150 mRNAs, respectively, corresponding to almost 20% of the yeast genome and roughly 36% of all transcriptional events each [2].
• This aberrant accumulation of Mex67p with RNA and the cold-sensitive growth phenotype of a dbp5 allele are suppressed by a mex67 mutation [3].
• The Glc7p nuclear phosphatase promotes mRNA export by facilitating association of Mex67p with mRNA [4].
• Here, we show that the Mex67p/Mtr2p complex binds to all of the repeat types (GLFG, FXFG, and FG) found in nucleoporins [5].

Biological context of MEX67

• Importantly, although accumulation of Mex67p-containing mRNPs is also observed when a nuclear basket component is mutated, these mRNPs still contain the nuclear export factor Yra1p [3].
• Interestingly, a mutant GAL2 gene lacking the coding region is still able to recruit Mex67p upon transcriptional activation and to relocate to the nuclear periphery [6].

Anatomical context of MEX67

• It is not known how Mex67p and Mtr2p, which form a heterodimer essential for mRNA export, transport mRNPs through the nuclear pore [5].

Associations of MEX67 with chemical compounds

• In vivo tests show that its export requires two proteins with putative leucine-rich nuclear export signals: Gle1p, Mex67p, and several additional nuclear and nuclear pore complex-associated proteins [7].

Physical interactions of MEX67

• Moreover, Mex67 bound mRNA accumulates at the nuclear rim in a temperature-sensitive dbp5 mutant when the nuclear exosome is impaired [3].
• Yra1p interacts directly with the mRNA transport factor Mex67p/Mtr2p, which is associated with the nuclear pore [8].

Regulatory relationships of MEX67

• These observations support the idea that Yra1p promotes mRNA export by facilitating the recruitment of Mex67p to the mRNP [9].

Other interactions of MEX67

• Binding of the Mex67p/Mtr2p heterodimer to FXFG, GLFG, and FG repeat nucleoporins is essential for nuclear mRNA export [5].
• In addition, ZDS1 interacted genetically with mutant alleles of genes encoding key factors in mRNA export, including DBP5 and MEX67 [10].
• The DEAD-box protein Dbp5p is required to dissociate Mex67p from exported mRNPs at the nuclear rim [3].
• At the nuclear pores, Nup85p represents one of the targets with which the Mex67p-Mtr2p complex interacts [1].
• Furthermore, other polymerase II transcripts encoding the transcriptional repressor ASH1 and the glycolytic enzyme PGK1 are shown to require Mex67p for their export into the cytoplasm [11].

References