Trax (translin-associated factor X), a primarily cytoplasmic protein, inhibits the binding of TB-RBP (translin) to RNA.
Trax (Translin-associated factor X) has been shown to interact with TB-RBP/Translin by its coimmunoprecipitation and in yeast two-hybrid assays. Here we demonstrate that Trax is widely expressed, does not bind to DNA or RNA, but forms heterodimers with TB-RBP under reducing conditions. The heterodimer of TB-RBP and Trax inhibits TB-RBP binding to RNA, but enhances TB-RBP binding to specific single stranded DNA sequences. The in vitro interactions between TB-RBP and Trax are confirmed by similar interactions in the yeast two-hybrid system. Cell fractionation and confocal microscope studies reveal that Trax is predominantly cytoplasmic. In contrast, TB-RBP is present in both the nuclei and cytoplasm of transfected cells and uses a highly conserved nuclear export signal to exit nuclei. In addition to a leucine zipper, two basic domains in TB-RBP are essential for RNA binding, but only one of these domains is needed for DNA binding. Trax restores DNA binding to TB-RBP containing an altered form of this domain. These data suggest that Trax-TB.RBP interactions modulate the DNA- and RNA-binding activity of TB-RBP.
Chennathukuzhi
V M
VM
Department of Obstetrics and Gynecology, Center for Research on Reproduction and Women's Health, School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6142, USA.
Kurihara
Y
Y
Bray
J D
JD
Hecht
N B
NB
D016475:3T3 Cells; D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000818:Animals; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D002467:Cell Nucleus / Q000378:metabolism; D003001:Cloning, Molecular; D017124:Conserved Sequence; D004277:DNA, Single-Stranded / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics; D006801:Humans; D051379:Mice; D008869:Microtubule-Associated Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D016297:Mutagenesis, Site-Directed; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D021381:Protein Transport; D012313:RNA / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D014162:Transfection
D002352:Carrier Proteins; D004277:DNA, Single-Stranded; D004268:DNA-Binding Proteins; D008869:Microtubule-Associated Proteins; D009687:Nuclear Proteins; D016601:RNA-Binding Proteins; D011994:Recombinant Proteins; C490551:STRBP protein, human; C095563:TSN protein, human; C498305:TSNAX protein, human; C498303:Tsn protein, mouse; C498306:Tsnax protein, mouse; D012313:RNA