Importin 13: a novel mediator of nuclear import and export

Mingot, José-Manuel; Kostka, Susanne; Kraft, Regine; Hartmann, Enno; Görlich, Dirk

doi:10.1093/emboj/20.14.3685

Cited by 204 publications

(243 citation statements)

References 63 publications

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“…Importin 13 has been demonstrated to be involved in Ranmediated nuclear transport of UBC9 and presumably with Ranmediated transport of SUMO-modified proteins (42). The nuclear pore contains several proteins that are either SUMOylated or that are components of the SUMOylation machinery, including RanBP2 (Ran-binding protein 2).…”

Section: Resultsmentioning

confidence: 99%

“…Molecular Modeling of the cSHMT-UBC9 Interaction-UBC9 from the crystal structure of a RanGAP1-UBC9 complex (23) (Protein Data Bank entry 1KPS) was manually docked with human cSHMT (Protein Data Bank entry 1BJ4) using the program O (24), positioning the molecules so that Lys 38 and Asn 42 of cSHMT chain A occupied approximately the same positions as Lys 526 and Glu 528 of RanGAP1, relative to UBC9 residues 86 -93. After overall molecular placement, side chains at the cSHMT-UBC9 interface were manually adjusted, and energy minimization of the complex was carried out using CNS (25).…”

Section: Methodsmentioning

confidence: 99%

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Evidence for Small Ubiquitin-like Modifier-dependent Nuclear Import of the Thymidylate Biosynthesis Pathway

Woeller

Anderson

Szebenyi

et al. 2007

Journal of Biological Chemistry

116

136

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Perturbations in folate-mediated one-carbon metabolism increase rates of uracil misincorporation into DNA during replication, impair cellular methylation reactions, and increase risk for neural tube defects and cancer. One-carbon metabolism is compromised by folate deficiency and common genetic polymorphisms. In this study, the mechanism for the preferential partitioning of cytoplasmic serine hydroxymethyltransferase (cSHMT)-derived methylenetetrahydrofolate to de novo thymidylate biosynthesis was investigated. The cSHMT enzyme was shown to interact with UBC9 and was a substrate for UBC9-catalyzed small ubiquitin-like modifier (SUMO) modification in vitro. SUMOylated cSHMT was detected in extracts from S phase MCF-7 cells, and cSHMT was shown to localize to the nucleus and nuclear periphery during the S and G 2 /M phases of the cell cycle. A common single nucleotide polymorphism (L474F-cSHMT) impaired the UBC9-cSHMT interaction and inhibited cSHMT SUMOylation in vitro. The three folate-dependent enzymes that constitute the de novo thymidylate biosynthesis pathway, cSHMT, thymidylate synthase, and dihydrofolate reductase, all contain SUMO modification consensus sequences. Compartmentation of the folate-dependent de novo thymidylate biosynthesis pathway in the nucleus accounts for the preferential partitioning of cSHMT-derived folate-activated one-carbon units into thymidylate biosynthesis; the efficiency of nuclear folate metabolism is likely to be modified by the cSHMT L474F polymorphism.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Evidence for Small Ubiquitin-like Modifier-dependent Nuclear Import of the Thymidylate Biosynthesis Pathway

Woeller

Anderson

Szebenyi

et al. 2007

Journal of Biological Chemistry

116

136

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“…The following transport receptors were expressed in E. coli JM109 or TG1 as described in the literature indicated and were purified on nickel nitrilotriacetic acid-agarose (Qiagen): Xenopus importin ␣1 (35), human importin ␤ (36), transportin 1 (37), Xenopus importin 7, human importin 5 (38), murine importin 9 (39), human importin 13 (40), and human exportin 1/Crm1 (41). Expression and purification of RanQ69L were performed as described (42).…”

Section: Site-directed Mutagenesis-nucleotide Exchanges In Rfp-mentioning

confidence: 99%

“…Additionally, we compared the binding of NC2 with that of another importin 13 substrate, the sumo-conjugating enzyme UBC9 (40). For that purpose, we generated different importin 13 deletion constructs and tested their NC2 binding potentials (Fig.…”

mentioning

confidence: 99%

Regulation of Nuclear Import and Export of Negative Cofactor 2

Kahle

Piaia

Neimanis

et al. 2009

Journal of Biological Chemistry

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The negative cofactor 2 (NC2) is a protein complex composed of two subunits, NC2␣ and NC2␤, and plays a key role in transcription regulation. Here we investigate whether each subunit contains a nuclear localization signal (NLS) that permits individual crossing of the nuclear membrane or whether nuclear import of NC2␣ and NC2␤ depends on heterodimerization. Our results from in vitro binding studies and transfection experiments in cultured cells show that each subunit contains a classical NLS (cNLS) that is recognized by the importin ␣/␤ heterodimer. Regardless of the individual cNLSs the two NC2 subunits are translocated as a preassembled complex as cotransfection experiments with wild-type and cNLS-deficient NC2 subunits demonstrate. Ran-dependent binding of the nuclear export receptor Crm1/exportin 1 confirmed the presence of a leucine-rich nuclear export signal (NES) in NC2␤. In contrast, NC2␣ does not exhibit a NES. Our results from interspecies heterokaryon assays suggest that heterodimerization with NC2␣ masks the NES in NC2␤, which prevents nuclear export of the NC2 complex. A mutation in either one of the two cNLSs decreases the extent of importin ␣/␤-mediated nuclear import of the NC2 complex. In addition, the NC2 complex can enter the nucleus via a second pathway, facilitated by importin 13. Because importin 13 binds exclusively to the NC2 complex but not to the individual subunits this alternative import pathway depends on sequence elements distributed among the two subunits. The negative cofactor 2 (NC2)2 is a protein complex composed of two subunits, NC2␣ (DRAP1) and NC2␤ (Dr1). Both subunits are conserved in eukaryotes and essential for Saccharomyces cerevisae viability (1, 2). NC2␣ and NC2␤ heterodimerize via histone-fold domains and associate with the promotor-bound TATA-binding protein (3, 4). The resulting NC2-TATA-binding protein-DNA complex sterically hinders the recruitment of transcription factor IIB and in part of transcription factor IIA (5), and thus inhibits transcription initiation (6, 7). The NC2 complex is present on a substantial fraction of human genes (8). Besides mediating TATA-binding protein binding to TATA-containing and TATA-less promoters (9) the NC2 complex can also mobilize TATA-binding protein on the DNA (10). In addition to the well established function as transcriptional repressor (11) several studies have shown that NC2 activates transcription, in vitro and in vivo (12-16). The mechanism underlying the positive effects of NC2 on gene expression is not understood. Although the two NC2 subunits mostly function together, recent studies in S. cerevisae (17), Drosophila (18), and human provided evidence that NC2␣ and NC2␤ can associate with different proteins (19 -21). In this study, we have analyzed whether human NC2 subunits contain localization signals that permit individual crossing of the nuclear membrane or whether nuclear import of NC2␣ and NC2␤ depends on heterodimerization.During interphase the exclusive site of nucleocytoplasmic exchange is the nuclear pore complex...

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“…For example, importin 13 (IPO13) has also been shown to have export capacity for the translation initiation factor elF1A (Mingot et al , 2001), and also exportin 4 (XPO4) has a bidirectional transport capability (Gontan et al , 2009). A specialized member of the importin β family is the cellular apoptosis susceptibility (CAS/XPO2) protein that is a recycling factor for importin αs (Kutay et al , 1997).…”

Section: Introductionmentioning

confidence: 99%

Landscape of nuclear transport receptor cargo specificity

Mackmull

Klaus

Heinze

et al. 2017

Molecular Systems Biology

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Nuclear transport receptors (NTRs) recognize localization signals of cargos to facilitate their passage across the central channel of nuclear pore complexes (NPCs). About 30 different NTRs constitute different transport pathways in humans and bind to a multitude of different cargos. The exact cargo spectrum of the majority of NTRs, their specificity and even the extent to which active nucleocytoplasmic transport contributes to protein localization remains understudied because of the transient nature of these interactions and the wide dynamic range of cargo concentrations. To systematically map cargo–NTR relationships in situ, we used proximity ligation coupled to mass spectrometry (BioID). We systematically fused the engineered biotin ligase BirA* to 16 NTRs. We estimate that a considerable fraction of the human proteome is subject to active nuclear transport. We quantified the specificity and redundancy in NTR interactions and identified transport pathways for cargos. We extended the BioID method by the direct identification of biotinylation sites. This approach enabled us to identify interaction interfaces and to discriminate direct versus piggyback transport mechanisms. Data are available via ProteomeXchange with identifier PXD007976.

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Importin 13: a novel mediator of nuclear import and export

Cited by 204 publications

References 63 publications

Evidence for Small Ubiquitin-like Modifier-dependent Nuclear Import of the Thymidylate Biosynthesis Pathway

Evidence for Small Ubiquitin-like Modifier-dependent Nuclear Import of the Thymidylate Biosynthesis Pathway

Regulation of Nuclear Import and Export of Negative Cofactor 2

Landscape of nuclear transport receptor cargo specificity

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