The export of mRNA from the nucleus to the cytoplasm is a multistep process that is mediated by mRNA-protein complexes (mRNP). The formation of mRNP begins by recruitment of some mRNA export factors to the elongating transcripts followed by targeting of the mRNP to the nuclear pore complex (NPC). The mRNP-complex is then translocation through the NPC channel. Finally the mRNP-complex is dissembled in the cytoplasm so that the RNA can be translated and mRNA export factors are returned to the nucleus for another round of mRNA export. We found that Uap56p is not essential for splicing in S. pombe, and its mRNA export functions do not require a functional ATP-binding pocket or catalytic residues of the RNA-helicase, DECD box. However, RNA binding was critical for Uap56p to function in mRNA export. We show that Uap56p functions non-enzymatically in mRNA export presumably as part of the mRNP-export. Our data suggests that Uap56p likely shuttles between the nucleus and the cytoplasm. We found Uap56p has both import and export signal and that the NPC associated protein Rae1p functions as its nuclear export receptor. Dss1p is a known component of the proteosomal subunit (19S subunit) it interacts with BRCA-2 in DNA repair. We have previously shown that Dss1p also interacts with Rae1p in mRNA export. We have recently found that Dss1 and Rae1p together function in DNA repair. We are investigating how Rae1p functions in the DNA repair process and whether other mRNA export factors are used by the DNA repair machinery.
| Thakurta, Anjan G; Gopal, Ganesh; Yoon, Jin Ho et al. (2004) Conserved nuclear export sequences in Schizosaccharomyces pombe Mex67 and human TAP function in mRNA export by direct nuclear pore interactions. J Biol Chem 279:17434-42 |
