Differential Modes of Nuclear Localization Signal (NLS) Recognition by Three Distinct Classes of NLS Receptors

Miyamoto, Yoichi; Imamoto, Naoko; Sekimoto, Takeyuki; Tachibana, Taro; Seki, Tsunetake; Tada, Shusuke; Enomoto, Takemi; Yoneda, Yoshihiro

doi:10.1074/jbc.272.42.26375

Cited by 161 publications

(140 citation statements)

References 51 publications

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“…Thus, the nuclear translocation of Ku70 and Ku80 may be regulated by binding with di erent NLS receptors. Indeed, recently, a number of NLS receptors have been identi®ed (Yoneda, 1997) and the existence of at least three structurally and functionally distinct NLS receptors was reported in a human single cell population (Miyamoto et al, 1997). Thus, we speculate that the nuclear translocation of Ku proteins might be controlled (at least in part) at the NLS recognition step, and that this might be regulated by NLS receptors with various speci®cities in vivo.…”

Section: Discussionmentioning

confidence: 80%

Ku80 can translocate to the nucleus independent of the translocation of Ku70 using its own nuclear localization signal

Koike¹,

Ikuta

Miyasaka³

et al. 1999

Oncogene

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Ku antigen is a complex of Ku70 and Ku80 subunits and plays an important role in not only DNA double-strand breaks (DSB) repair and V(D)J recombination, but also in growth regulation. Ku is generally believed to always form and function as heterodimers on the basis of in vitro observations. Here we demonstrate that the localization of Ku80 does not completely coincide with that of Ku70. Ku70 and Ku80 were colocalized in the nucleus in the interphase but not in the late telophase/early G1 phase of the cell cycle. Since the in vivo function of Ku might be partially regulated by the control of its transport, we attempted to investigate the molecular mechanisms underlying the nuclear translocation of Ku. The nuclear translocation of Ku80 started during the late telophase/ early G1 phase after the nuclear envelope was formed and this was preceded by the nuclear translocation of Ku70. Furthermore, we found that the Ku80 protein was transported to the nucleus without heterodimerization with Ku70. To understand in detail the mechanism of transport of Ku80, we attempted to identify the nuclear localization signal (NLS) of Ku80 and de®ned to a region spanning nine amino acid residues (positions 561 ± 569). The Ku80 NLS was demonstrated to be mediated to the nuclear rim by two components of PTAC58 and PTAC97. All these ®ndings support the idea that Ku80 can translocate to the nucleus using its own NLS independent of the translocation of Ku70.

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Section: Discussionmentioning

confidence: 80%

Ku80 can translocate to the nucleus independent of the translocation of Ku70 using its own nuclear localization signal

Koike¹,

Ikuta

Miyasaka³

et al. 1999

Oncogene

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“…The proximal basic cluster of the bipartite NLS is separated by 15 amino acids from an upstream pair of lysines. This fits the very precise requirements for the consensus NLS from DNA Helicase-Q1, 22 a homologue of the E. coli RecQ Helicase. 40 The NLS for DNA Helicase Q1 has its own chaperone protein, the QIP1 protein, homologous to the importin-alpha NLS receptor.…”

Section: Control Of Af4 Subcellular Localizationmentioning

confidence: 99%

“…The QIP-1 protein, unlike the two other classes of NLS receptor proteins represented by the proteins Rch1 and NPI-1, binds very discriminately to the specific sequence described. 22 To test the function of the putative NLS in the murine AF4 sequence, a series of constructs were engineered with the pEGFP plasmid vector (Figure 1b). The largest fragment tested, which consists of full-length murine AF4, lacking the first six amino acids, and the terminal 40 amino acids, displayed a punctate pattern of nuclear expression (Figure 2a).…”

Section: Control Of Af4 Subcellular Localizationmentioning

confidence: 99%

“…18,21 The AF4 (or FEL) gene fuses with MLL in the t(4;11)(q21;q23), and is the most common MLL fusion partner. 22 In all, 95% of MLL-AF4-associated leukemia is classified as ALL, but shows some lineage infidelity, typically expressing a CD19 þ CD10 À CD15 þ phenotype. 23 AF4 is a serine/proline-rich nuclear protein with transcriptional activation domains.…”

Section: Introductionmentioning

confidence: 99%

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MLL fusion partners AF4 and AF9 interact at subnuclear foci

et al. 2003

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The MLL gene is involved in translocations associated with both acute lymphoblastic and acute myelogenous leukemia. These translocations fuse MLL with one of over 30 partner genes. Collectively, the MLL partner genes do not share a common structural motif or biochemical function. We have identified a protein interaction between the two most common MLL fusion partners AF4 and AF9. This interaction is restricted to discrete nuclear foci we have named 'AF4 bodies'. The AF4 body is non-nucleolar and is not coincident with any known nuclear structures we have examined. The AF4-AF9 interaction is maintained by the MLL-AF4 fusion protein, and expression of the MLL-AF4 fusion can alter the subnuclear localization of AF9. In view of other research indicating that other MLL fusion partners also interact with one another, these results suggest that MLL fusion partners may participate in a web of protein interactions with a common functional goal. The disruption of this web of interactions by fusion with MLL may be important to leukemogenesis.

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“…The directionality of the nuclear import is conferred by an asymmetric distribution of the GTP and GDP-bound forms of Ran between the cytoplasm and the nucleus, with the GTP-form predominant in the nucleus [12,13]. Based on the similarities of their primary structures, the importins a have been separated into three subfamilies, each of which shows distinct substrate specificity and differential expression [14][15][16]. Importins a consist of two structural and functional domains, a short basic N-terminal importin b binding (IBB) domain, and a large NLS-binding domain comprising armadillo (Arm) repeats [17][18][19].…”

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confidence: 99%

Importin α binds to an unusual bipartite nuclear localization signal in the heterogeneous ribonucleoprotein type I

Romanelli

Morandi

2002

European Journal of Biochemistry

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The heterogeneous nuclear ribonucleoprotein (hnRNP) type I, a modulator of alternative splicing, localizes in the nucleoplasm of mammalian cells and in a discrete perinucleolar structure. HnRNP I contains a novel type of bipartite nuclear localization signal (NLS) at the N-terminus of the protein that we have previously named nuclear determinant localization type I (NLD-I). Recently, a neural counterpart of hnRNP I has been identified that contains a putative NLS with two strings of basic amino acids separated by a spacer of 30 residues. In the present study we show that the neural hnRNP I NLS is necessary and sufficient for nuclear localization and represents a variant of the novel bipartite NLS present in the NLD-I domain. Furthermore, we demonstrate that the NLD-I is transported into the nucleus by cytoplasmic factor(s) with active transport modality. Binding assays using recombinant importin a show an interaction with NLD-I similar to that of SV40 large T antigen NLS. Deletion analysis indicates that both stretches of basic residues are necessary for binding to importin a. The above experimental results lead to the conclusion that importin a acts as cytoplasmic receptor for proteins characterized by a bipartite NLS signal that extends up to 37 residues.Keywords: heterogeneous ribonucleoprotein-I; polypyrimidine tract-binding protein; PTB; nuclear localization signal; importin a.Transport of proteins and RNA into and out of the nucleus occurs through nuclear pore complexes (NPCs), which are plugged through the double membrane of the nuclear envelope [1,2]. Small molecules and ions may pass the NPC passively, while macromolecules larger than 40-45 kDa are actively transported through the NPC. The active nuclear import and export of proteins is mediated by specific aminoacid sequences that are referred as nuclear localization signals (NLSs) [3,4] and nuclear export signal (NESs) [5]. At least two different types of ÔclassicalÕ NLSs have been defined: a short stretch of basic amino acids, exemplified by the SV40 large T antigen NLS (T-ag PKKKRKV) [6] and a bipartite NLS composed of two stretches of basic amino acids separated by a spacer of 10-12 amino acids, exemplified by nucleoplasmin (KRPAATKKAGQAKKKK). The two sets of basic residues of bipartite-type NLS are required for sufficient nuclear localization, while the spacer is mutant-tolerant in sequence [7]. NLSs are usually recognized by the heterodimeric import receptor complex comprising importins a and b, also named karyopherins [8,9]. Importins a contain the NLS-binding site and importins b are responsible for the docking of the importin-substrate complex to the cytoplasmic side of the NPC and its subsequent translocation through the pore. Transfer through the pore of importin-NLS protein complex requires two additional soluble proteins, RanGTPase and nuclear transport factor-2 (NTF2) [1]. Once inside the nucleus, Ran-GTP binding to importin b causes the dissociation of the import complex and release of the cargo [10,11]. The directionality of the nuclear...

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Differential Modes of Nuclear Localization Signal (NLS) Recognition by Three Distinct Classes of NLS Receptors

Cited by 161 publications

References 51 publications

Ku80 can translocate to the nucleus independent of the translocation of Ku70 using its own nuclear localization signal

Ku80 can translocate to the nucleus independent of the translocation of Ku70 using its own nuclear localization signal

MLL fusion partners AF4 and AF9 interact at subnuclear foci

Importin α binds to an unusual bipartite nuclear localization signal in the heterogeneous ribonucleoprotein type I

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