Mutational analysis of human prothymosin α reveals a bipartite nuclear localization signal

Mammalian Stau1 (Staufen1), a modular protein composed of several dsRBDs (double-stranded RNA-binding domains), is probably involved in mRNA localization. Although Stau1 is mostly described in association with the rough endoplasmic reticulum and ribosomes in the cytoplasm, recent studies suggest that it may transit through the nucleus/nucleolus. Using a sensitive yeast import assay, we show that Stau1 is actively imported into the nucleus through a newly identified bipartite nuclear localization signal. As in yeast, the bipartite nuclear localization signal is necessary for Stau1 nuclear import in mammalian cells. It is also required for Stau1 nucleolar trafficking. However, Stau1 nuclear transit seems to be regulated by mechanisms that involve cytoplasmic retention and/or facilitated nuclear export. Cytoplasmic retention is mainly achieved through the action of dsRBD3, with dsRBD2 playing a supporting role in this function. Similarly, dsRBD3, but not its RNA-binding activity, is critical for Stau1 nucleolar trafficking. The function of dsRBD3 is strengthened or stabilized by the presence of dsRBD4 but prevented by the interdomain between dsRBD2 and dsRBD3. Altogether, these results suggest that Stau1 nuclear trafficking is a highly regulated process involving several determinants. The presence of Stau1 in the nucleus/nucleolus suggests that it may be involved in ribonucleoprotein formation in the nucleus and/or in other nuclear functions not necessarily related to mRNA transport.

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Hairless is translocated to the nucleus via a novel bipartite nuclear localization signal and is associated with the nuclear matrix

Journal of Cell Science ◽

10.1242/jcs.114.2.367 ◽

2001 ◽

Vol 114 (2) ◽

pp. 367-376

Author(s):

K. Djabali ◽

V.M. Aita ◽

A.M. Christiano

Keyword(s):

Amino Acid ◽

Hair Follicle ◽

Nuclear Localization ◽

Nuclear Matrix ◽

Nuclear Localization Signal ◽

Amino Acid Residues ◽

Bipartite Nuclear Localization Signal ◽

Hairless Gene ◽

Fractionation Analysis ◽

Localization Signal

Hair follicle cycling is an exquisitely regulated and dynamic process consisting of phases of growth, regression and quiescence. The transitions between the phases are governed by a growing number of regulatory proteins, including transcription factors. The hairless (hr) gene encodes a putative transcription factor that is highly expressed in the skin, where it appears to be an essential regulator during the regression of the catagen hair follicle. In hairless mice, as well as humans with congenital atrichia, the absence of hr gene function initiates a premature and abnormal catagen due to a dysregulation of apoptosis and cell adhesion, and defects in the signaling required for hair follicle remodeling. Here, we report structure-function studies of the hairless gene product, in which we identify a novel bipartite nuclear localization signal (NLS) of the form KRA(X13) PKR. Deletion analysis of the mouse hr gene mapped the NLS to amino acid residues 409–427. Indirect immunofluorescence microscopy of cells transiently transfected with hairless-green fluorescent fusion proteins demonstrated that these amino acid residues are necessary and sufficient for nuclear localization. Furthermore, nuclear fractionation analysis revealed that the hr protein is associated with components of the nuclear matrix.

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Identification of a novel bipartite nuclear localization signal in the DNA polymerase of the betabaculovirus Pieris rapae granulovirus

Archives of Virology ◽

10.1007/s00705-018-4115-0 ◽

2018 ◽

Vol 164 (3) ◽

pp. 839-845

Author(s):

Pei Li ◽

Lijuan Wu ◽

Guoqing Chen

Keyword(s):

Dna Polymerase ◽

Nuclear Localization ◽

Nuclear Localization Signal ◽

Pieris Rapae ◽

Bipartite Nuclear Localization Signal ◽

Localization Signal

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The Sts1 nuclear import adapter uses a non-canonical bipartite nuclear localization signal and is directly degraded by the proteasome

Journal of Cell Science ◽

10.1242/jcs.236158 ◽

2020 ◽

Vol 133 (6) ◽

pp. jcs236158

Author(s):

Lauren Budenholzer ◽

Carolyn Breckel ◽

Christopher M. Hickey ◽

Mark Hochstrasser

Keyword(s):

Nuclear Localization ◽

Nuclear Import ◽

Nuclear Localization Signal ◽

Bipartite Nuclear Localization Signal ◽

Localization Signal

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Mutational analysis of the EMCV 2A protein identifies a nuclear localization signal and an eIF4E binding site

Virology ◽

10.1016/j.virol.2010.11.002 ◽

2011 ◽

Vol 410 (1) ◽

pp. 257-267 ◽

Cited By ~ 22

Author(s):

Rachel Groppo ◽

Bradley A. Brown ◽

Ann C. Palmenberg

Keyword(s):

Binding Site ◽

Nuclear Localization ◽

Nuclear Localization Signal ◽

Mutational Analysis ◽

Localization Signal

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The N-Terminal Domain of IκBα Masks the Nuclear Localization Signal(s) of p50 and c-Rel Homodimers

Molecular and Cellular Biology ◽

10.1128/mcb.18.5.2640 ◽

1998 ◽

Vol 18 (5) ◽

pp. 2640-2649 ◽

Cited By ~ 48

Author(s):

Matthew Latimer ◽

Mary K. Ernst ◽

Linda L. Dunn ◽

Marina Drutskaya ◽

Nancy R. Rice

Keyword(s):

Amino Acids ◽

Transcription Factors ◽

Nuclear Localization ◽

Nuclear Localization Signal ◽

Mutational Analysis ◽

Inhibitor Protein ◽

N Terminus ◽

Localization Signal ◽

Terminal Section ◽

Rel Homology Domain

ABSTRACT Members of the Rel/NF-κB family of transcription factors are related to each other over a region of about 300 amino acids called the Rel Homology Domain (RHD), which governs DNA binding, dimerization, and binding to inhibitor. At the C-terminal end of the RHD, each protein has a nuclear localization signal (NLS). The crystal structures of the p50 and RelA family members show that the RHD consists of two regions: an N-terminal section which contains some of the DNA contacts and a C-terminal section which contains the remaining DNA contacts and controls dimerization. In unstimulated cells, the homo- or heterodimeric Rel/NF-κB proteins are cytoplasmic by virtue of binding to an inhibitor protein (IκB) which somehow masks the NLS of each member of the dimer. The IκB proteins consist of an ankyrin-repeat-containing domain that is required for binding to dimers and N- and C-terminal domains that are dispensable for binding to most dimers. In this study, we examined the interaction between IκBα and Rel family homodimers by mutational analysis. We show that (i) the dimerization regions of p50, RelA, and c-Rel are sufficient for binding to IκBα, (ii) the NLSs of RelA and c-Rel are not required for binding to IκBα but do stabilize the interaction, (iii) the NLS of p50 is required for binding to IκBα, (iv) only certain residues within the p50 NLS are required for binding, and (v) in a p50-IκBα complex or a c-Rel-IκBα complex, the N terminus of IκBα either directly or indirectly masks one or both of the dimer NLSs.

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