scholarly journals Functional domains in nuclear import factor p97 for binding the nuclear localization sequence receptor and the nuclear pore.

1997 ◽  
Vol 8 (6) ◽  
pp. 945-956 ◽  
Author(s):  
N C Chi ◽  
S A Adam
Keyword(s):  
Nuclear Localization ◽  
Receptor Binding ◽  
Protein Import ◽  
Binding Domain ◽  
Nuclear Localization Sequence ◽  
Functional Domains ◽  
Nuclear Pore ◽  
Binding Domains ◽  
Localization Sequence ◽  
Ran Gtp

The interaction of the nuclear protein import factor p97 with the nuclear localization sequence (NLS) receptor, the nuclear pore complex, and Ran/TC4 is important for coordinating the events of protein import to the nucleus. We have mapped the binding domains on p97 for the NLS receptor and the nuclear pore. The NLS receptor-binding domain of p97 maps to the C-terminal 60% of the protein between residues 356 and 876. The pore complex-binding domain of p97 maps to residues 152-352. The pore complex-binding domain overlaps the Ran-GTP- and Ran-GDP-binding domains on p97, but only Ran-GTP competes for docking in permeabilized cells. The N-ethylmaleimide sensitivity of the p97 for docking was investigated and found to be due to inhibition of p97 binding to the pore complex and to the NLS receptor. Site-directed mutagenesis of conserved cysteine residues in the pore- and receptor-binding domains identified two cysteines, C223 and C228, that were required for p97 to bind the nuclear pore. Inhibition studies on docking and accumulation of a NLS protein provided additional evidence that the domains identified biochemically are the functional domains involved in protein import. Together, these results suggest that Ran-GTP dissociates the receptor complex and prevents p97 binding to the pore by inducing a conformational change in the structure of p97 rather than simple competition for binding sites.

Novel properties of the protein kinase CK2-site-regulated nuclear- localization sequence of the interferon-induced nuclear factor IFI 16

2000 ◽  
Vol 353 (1) ◽  
pp. 69-77 ◽  
Author(s):  
Lyndall J. BRIGGS ◽  
Ricky W. JOHNSTONE ◽  
Rachel M. ELLIOT ◽  
Chong-Yun XIAO ◽  
Michelle DAWSON ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Nuclear Localization ◽  
Nuclear Import ◽  
Protein Kinase Ck2 ◽  
Protein Import ◽  
Simian Virus 40 ◽  
Simian Virus ◽  
Nuclear Localization Sequence ◽  
Localization Sequence ◽  
Kinase Ck2

Members of the interferon-induced class of nuclear factors possess a putative CcN motif, comparable with that within proteins such as the simian virus 40 large tumour antigen (T-ag), which confers phosphorylation-mediated regulation of nuclear-localization sequence (NLS)-dependent nuclear import. Here we examine the functionality of the interferon-induced factor 16 (IFI 16) CcN motif, demonstrating its ability to target a heterologous protein to the nucleus, and to be phosphorylated specifically by the CcN-motif-phosphorylating protein kinase CK2 (CK2). The IFI 16 NLS, however, has novel properties, conferring ATP-dependent nuclear import completely independent of cytosolic factors, as well as binding to nuclear components. The IFI 16 NLS is not recognized with high affinity by the NLS-binding importin heterodimer, and transport mediated by it is insensitive to non-hydrolysable GTP analogues. The IFI 16 NLS thus mediates nuclear import through a pathway completely distinct from that of conventional NLSs, such as that of T-ag, but intriguingly resembling that of the NLS of the HIV-1 transactivator protein Tat. Since the IFI 16 CK2 site enhances nuclear import through facilitating binding to nuclear components, this represents a novel mechanism by which the site regulates nuclear-protein import, and constitutes a difference between the IFI 16 and Tat NLSs that may be of importance in the immune response.

scholarly journals Functional Analysis of Tpr: Identification of Nuclear Pore Complex Association and Nuclear Localization Domains and a Role in mRNA Export

1998 ◽  
Vol 143 (7) ◽  
pp. 1801-1812 ◽  
Author(s):  
Peter Bangs ◽  
Brian Burke ◽  
Christine Powers ◽  
Roger Craig ◽  
Aruna Purohit ◽  
...  
Keyword(s):  
Nuclear Localization ◽  
Nuclear Pore Complex ◽  
Ectopic Expression ◽  
Coiled Coil ◽  
Full Length ◽  
Nuclear Localization Sequence ◽  
Nuclear Pore ◽  
Nuclear Interior ◽  
Mammalian Cell Lines ◽  
Localization Sequence

Tpr is a 270-kD coiled-coil protein localized to intranuclear filaments of the nuclear pore complex (NPC). The mechanism by which Tpr contributes to the structure and function of the nuclear pore is currently unknown. To gain insight into Tpr function, we expressed the full-length protein and several subdomains in mammalian cell lines and examined their effects on nuclear pore function. Through this analysis, we identified an NH2-terminal domain that was sufficient for association with the nucleoplasmic aspect of the NPC. In addition, we unexpectedly found that the acidic COOH terminus was efficiently transported into the nuclear interior, an event that was apparently mediated by a putative nuclear localization sequence. Ectopic expression of the full-length Tpr caused a dramatic accumulation of poly(A)+ RNA within the nucleus. Similar results were observed with domains that localized to the NPC and the nuclear interior. In contrast, expression of these proteins did not appear to affect nuclear import. These data are consistent with a model in which Tpr is tethered to intranuclear filaments of the NPC by its coiled coil domain leaving the acidic COOH terminus free to interact with soluble transport factors and mediate export of macromolecules from the nucleus.

scholarly journals The cytoplasmic filaments of the nuclear pore complex are dispensable for selective nuclear protein import

2002 ◽  
Vol 158 (1) ◽  
pp. 63-77 ◽  
Author(s):  
Tobias C. Walther ◽  
Helen S. Pickersgill ◽  
Volker C. Cordes ◽  
Martin W. Goldberg ◽  
Terry D. Allen ◽  
...  
Keyword(s):  
Nuclear Pore Complex ◽  
Nuclear Import ◽  
Protein Import ◽  
Nuclear Localization Sequence ◽  
Nuclear Pore ◽  
Slight Reduction ◽  
Cytoplasmic Filaments ◽  
Localization Sequence ◽  
Importin Α

The nuclear pore complex (NPC) mediates bidirectional macromolecular traffic between the nucleus and cytoplasm in eukaryotic cells. Eight filaments project from the NPC into the cytoplasm and are proposed to function in nuclear import. We investigated the localization and function of two nucleoporins on the cytoplasmic face of the NPC, CAN/Nup214 and RanBP2/Nup358. Consistent with previous data, RanBP2 was localized at the cytoplasmic filaments. In contrast, CAN was localized near the cytoplasmic coaxial ring. Unexpectedly, extensive blocking of RanBP2 with gold-conjugated antibodies failed to inhibit nuclear import. Therefore, RanBP2-deficient NPCs were generated by in vitro nuclear assembly in RanBP2-depleted Xenopus egg extracts. NPCs were formed that lacked cytoplasmic filaments, but that retained CAN. These nuclei efficiently imported nuclear localization sequence (NLS) or M9 substrates. NPCs lacking CAN retained RanBP2 and cytoplasmic filaments, and showed a minor NLS import defect. NPCs deficient in both CAN and RanBP2 displayed no cytoplasmic filaments and had a strikingly immature cytoplasmic appearance. However, they showed only a slight reduction in NLS-mediated import, no change in M9-mediated import, and were normal in growth and DNA replication. We conclude that RanBP2 is the major nucleoporin component of the cytoplasmic filaments of the NPC, and that these filaments do not have an essential role in importin α/β– or transportin-dependent import.

scholarly journals Origin of the nuclear proteome on the basis of pre-existing nuclear localization signals in prokaryotic proteins

2020 ◽  
Author(s):  
Olga M. Lisitsyna ◽  
Margarita A. Kurnaeva ◽  
Eugene A. Arifulin ◽  
Maria Y. Shubina ◽  
Yana R. Musinova ◽  
...  
Keyword(s):  
Nuclear Localization ◽  
Protein Import ◽  
Eukaryotic Cell ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
Nuclear Localization Signals ◽  
Binding Domains ◽  
Nuclear Proteome ◽  
Pore Complexes ◽  
Open Question

AbstractThe origin of the selective nuclear protein import machinery, which consists of nuclear pore complexes and adaptor molecules interacting with the nuclear localization signals (NLSs) of cargo molecules, was one of the most important events in the evolution of the eukaryotic cell. How the proteins were selected for import into the forming nuclei remains an open question. Here, we demonstrate that functional NLSs may be integrated inside nucleotide-binding domains of both eukaryotic and prokaryotic proteins and may co-evolve with these domains. We propose that the pre-existence of NLSs inside prokaryotic proteins dictated, at least partially, the nuclear proteome composition.

scholarly journals Nuclear import ofArabidopsisPOLY(ADP-RIBOSE) POLYMERASE 2 is mediated by importin-α and a nuclear localization sequence located between the predicted SAP domains

2018 ◽  
Author(s):  
Chao Chen ◽  
Ruth Lintermann ◽  
Lennart Wirthmueller
Keyword(s):  
Nuclear Localization ◽  
Nuclear Import ◽  
Dna Lesions ◽  
Site Directed Mutagenesis ◽  
Covalent Attachment ◽  
Nuclear Localization Sequence ◽  
Diffusion Limit ◽  
Nuclear Pore ◽  
Localization Sequence ◽  
Importin Α

AbstractProteins of the poly(ADP-ribose) polymerase (PARP) family modify target proteins by covalent attachment of ADP-ribose moieties onto amino acid side chains. InArabidopsis, PARP proteins contribute to repair of DNA lesions and modulate plant responses to various abiotic and biotic stressors.ArabidopsisPARP1 and PARP2 are nuclear proteins and given that their molecular weights exceed the diffusion limit of nuclear pore complexes, an active import mechanism into the nucleus is likely. Here we use confocal microscopy of fluorescent protein-taggedArabidopsisPARP2 and PARP2 deletion constructs in combination with site-directed mutagenesis to identify a nuclear localization sequence in PARP2 that is required for nuclear import. We report that in co-immunoprecipitation assays PARP2 interacts with several isoforms of the importin-α group of nuclear transport adapters and that PARP2 binding to IMPORTIN-α2 is mediated by the identified nuclear localization sequence. Our results demonstrate that PARP2 is a cargo protein of the canonical importin-α/β nuclear import pathway.

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