scholarly journals Analysis of mutations in the putative nuclear localization sequence of interleukin-1β

1991 ◽  
Vol 280 (1) ◽  
pp. 111-116 ◽  
Author(s):  
S Grenfell ◽  
N Smithers ◽  
S Witham ◽  
A Shaw ◽  
P Graber ◽  
...  
Keyword(s):  
Nuclear Localization ◽  
Interleukin 1 ◽  
Simian Virus 40 ◽  
T Antigen ◽  
Nuclear Accumulation ◽  
Nuclear Localization Sequence ◽  
Target Cells ◽  
Wild Type ◽  
Receptor Mediated Endocytosis ◽  
Localization Sequence

Previous studies have shown that, after receptor-mediated endocytosis, interleukin-1 alpha (IL1 alpha) and interleukin-1 beta (IL1 beta) are translocated to the nucleus, where they appear to accumulate. It has been suggested that nuclear translocation may be involved in the biological responsiveness of target cells to IL1 stimulation. The human IL1 beta molecule contains a seven-amino-acid sequence (-Pro208-Lys-Lys-Lys-Met-Glu-Lys-) that shows some sequence identity with the nuclear localization sequence of the simian-virus-40 large T-antigen. The effects of point mutations within this putative nuclear localization sequence on IL1 beta binding, receptor-mediated endocytosis and biological activity have been characterized. Mutants M49 (Lys210→Ala), M50 (Lys211→Ala) and M51 (Pro208→Ala) all retained the ability to bind to the IL1 receptor, albeit with lower affinity than the wild-type molecules. However, mutants M49, M50 and M51 showed greater biological potency than wild-type IL1 alpha or IL1 beta, as measured by the induction of IL2 secretion. However, receptor-mediated endocytosis and nuclear accumulation of M50 were comparable with those in the wild-type. These observations suggest that the putative nuclear localization sequence may play an important role in the generation of biological responses to IL1 stimulation, even though it may not influence internalization of the ligand.

scholarly journals Functional Activity of the Fanconi Anemia Protein FAA Requires FAC Binding and Nuclear Localization

1998 ◽  
Vol 18 (10) ◽  
pp. 5952-5960 ◽  
Author(s):  
Dieter Näf ◽  
Gary M. Kupfer ◽  
Ahmed Suliman ◽  
Kathleen Lambert ◽  
Alan D. D’Andrea
Keyword(s):  
Nuclear Localization ◽  
Fanconi Anemia ◽  
Functional Activity ◽  
Simian Virus 40 ◽  
T Antigen ◽  
Nuclear Accumulation ◽  
Wild Type ◽  
Amino Terminal ◽  
Complementation Groups ◽  
Mutant Forms

ABSTRACT Fanconi anemia (FA) is an autosomal recessive disease characterized by genomic instability, cancer susceptibility, and cellular hypersensitivity to DNA-cross-linking agents. Eight complementation groups of FA (FA-A through FA-H) have been identified. Two FA genes, corresponding to complementation groups FA-A and FA-C, have been cloned, but the functions of the encoded FAA and FAC proteins remain unknown. We have recently demonstrated that FAA and FAC interact to form a nuclear complex. In this study, we have analyzed a series of mutant forms of the FAA protein with respect to functional activity, FAC binding, and nuclear localization. Mutation or deletion of the amino-terminal nuclear localization signal (NLS) of FAA results in loss of functional activity, loss of FAC binding, and cytoplasmic retention of FAA. Replacement of the NLS sequence with a heterologous NLS sequence, derived from the simian virus 40 T antigen, results in nuclear localization but does not rescue functional activity or FAC binding. Nuclear localization of the FAA protein is therefore necessary but not sufficient for FAA function. Mutant forms of FAA which fail to bind to FAC also fail to promote the nuclear accumulation of FAC. In addition, wild-type FAC promotes the accumulation of wild-type FAA in the nucleus. Our results suggest that FAA and FAC perform a concerted function in the cell nucleus, required for the maintenance of chromosomal stability.

Nuclear accumulation of p53 protein is mediated by several nuclear localization signals and plays a role in tumorigenesis

1990 ◽  
Vol 10 (12) ◽  
pp. 6565-6577
Author(s):  
G Shaulsky ◽  
N Goldfinger ◽  
A Ben-Ze'ev ◽  
V Rotter
Keyword(s):  
Nuclear Localization ◽  
Cell Nucleus ◽  
P53 Protein ◽  
Simian Virus 40 ◽  
T Antigen ◽  
Nuclear Accumulation ◽  
Mutant P53 ◽  
Wild Type ◽  
Nuclear Localization Signals ◽  
Wild Type P53

The basic carboxy terminus of p53 plays an important role in directing the protein into the nuclear compartment. The C terminus of the p53 molecule contains a cluster of several nuclear localization signals (NLSs) that mediate the migration of the protein into the cell nucleus. NLSI, the most active domain, is highly conserved in genetically diverged species and shares perfect homology with consensus NLS sequences found in other nuclear proteins. The other two NLSs, II and III, appear to be less effective and less conserved. Although nuclear localization is dictated primarily by the NLSs inherent in the primary amino acid sequence, the actual nuclear homing can be modified by interactions with other proteins expressed in the cell. Comparison between wild-type p53 and naturally occurring mutant p53 showed that both protein categories could migrate into the nucleus of rat primary embryonic fibroblasts by essentially similar mechanisms. Nuclear localization of both proteins was totally dependent on the existence of functional NLS domains. In COS cells, however, we found that NLS-deprived wild-type p53 molecules could migrate into the nucleus by complexing with another nuclear protein, simian virus 40 large-T antigen. Wild-type and mutant p53 proteins differentially complexed with viral or cellular proteins, which may significantly affect the ultimate compartmentalization of p53 in the cell; this finding suggests that the actual subcellular compartmentalization of proteins may differ in various cell type milieux and may largely be affected by the ability of these proteins to complex with other proteins expressed in the cell. Experiments designed to test the physiological significance of p53 subcellular localization indicated that nuclear localization of mutant p53 is essential for this protein to enhance the process of malignant transformation of partially transformed cells, suggesting that p53 functions within the cell nucleus.

scholarly journals Identification of the Nuclear Localization Signal inXenopus Cyclin E and Analysis of Its Role in Replication and Mitosis

2002 ◽  
Vol 13 (12) ◽  
pp. 4388-4400 ◽  
Author(s):  
Jonathan D. Moore ◽  
Sally Kornbluth ◽  
Tim Hunt
Keyword(s):  
Dna Replication ◽  
Nuclear Localization ◽  
Cyclin E ◽  
T Antigen ◽  
Cyclin B ◽  
Nuclear Accumulation ◽  
Nuclear Localization Sequence ◽  
Nuclear Targeting ◽  
Sv40 Large T Antigen ◽  
Localization Sequence

Cyclin-dependent kinase (Cdk)2/cyclin E is imported into nuclei assembled in Xenopus egg extracts by a pathway that requires importin-α and -β. Here, we identify a basic nuclear localization sequence (NLS) in the N-terminus ofXenopus cyclin E. Mutation of the NLS eliminated nuclear accumulation of both cyclin E and Cdk2, and such versions of cyclin E were unable to trigger DNA replication. Addition of a heterologous NLS from SV40 large T antigen restored both nuclear targeting of Cdk2/cyclin E and DNA replication. We present evidence indicating that Cdk2/cyclin E complexes must become highly concentrated within nuclei to support replication and find that cyclin A can trigger replication at much lower intranuclear concentrations. We confirmed that depletion of endogenous cyclin E increases the concentration of cyclin B necessary to promote entry into mitosis. In contrast to its inability to promote DNA replication, cyclin E lacking its NLS was able to cooperate with cyclin B in promoting mitotic entry.

scholarly journals Rat1p and Xrn1p are functionally interchangeable exoribonucleases that are restricted to and required in the nucleus and cytoplasm, respectively.

1997 ◽  
Vol 17 (10) ◽  
pp. 6122-6130 ◽  
Author(s):  
A W Johnson
Keyword(s):  
Fluorescent Protein ◽  
Simian Virus 40 ◽  
Simian Virus ◽  
T Antigen ◽  
Nuclear Localization Sequence ◽  
Wild Type ◽  
Gene Encoding ◽  
Cytoplasmic Rna ◽  
Localization Sequence ◽  
Green Fluorescent

XRN1 encodes an abundant cytoplasmic exoribonuclease, Xrn1p, responsible for mRNA turnover in yeast. A screen for bypass suppressors of the inviability of xrn1 ski2 double mutants identified dominant alleles of RAT1, encoding an exoribonuclease homologous with Xrn1p. These RAT1 alleles restored XRN1-like functions, including cytoplasmic RNA turnover, wild-type sensitivity to the microtubule-destabilizing drug benomyl, and sporulation. The mutations were localized to a region of the RAT1 gene encoding a putative bipartite nuclear localization sequence (NLS). Fusions to green fluorescent protein were used to demonstrate that wild-type Rat1p is localized to the nucleus and that the mutant alleles result in mislocalization of Rat1p to the cytoplasm. Conversely, targeting Xrn1p to the nucleus by the addition of the simian virus 40 large-T-antigen NLS resulted in complementation of the temperature sensitivity of a rat1-1 strain. These results indicate that Xrn1p and Rat1p are functionally interchangeable exoribonucleases that function in and are restricted to the cytoplasm and nucleus, respectively. It is likely that the higher eukaryotic homologs of these proteins will function similarly in the cytoplasm and nucleus.

scholarly journals Context affects nuclear protein localization in Saccharomyces cerevisiae.

1989 ◽  
Vol 9 (2) ◽  
pp. 384-389 ◽  
Author(s):  
M Nelson ◽  
P Silver
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Amino Acids ◽  
Nuclear Localization ◽  
Simian Virus 40 ◽  
Simian Virus ◽  
T Antigen ◽  
Single Amino Acid ◽  
Nuclear Localization Sequence ◽  
Localization Sequence ◽  
Beta Galactosidase

Proteins destined for the nucleus contain nuclear localization sequences, short stretches of amino acids responsible for targeting them to the nucleus. We show that the first 29 amino acids of GAL4, a yeast DNA-binding protein, function efficiently as a nuclear localization sequence when fused to normally cytoplasmic invertase, but not when fused to Escherichia coli beta-galactosidase. Moreover, the nuclear localization sequence from simian virus 40 T antigen functions better when fused to invertase than when fused to beta-galactosidase. A single amino acid change in the T-antigen nuclear localization sequence inhibits the nuclear localization of simian virus 40-invertase and simian virus 40-beta-galactosidase in Saccharomyces cerevisiae. From these results, we conclude that the relative ability of a nuclear localization sequence to act depends on the protein to which it is linked.

Context affects nuclear protein localization in Saccharomyces cerevisiae

1989 ◽  
Vol 9 (2) ◽  
pp. 384-389
Author(s):  
M Nelson ◽  
P Silver
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Amino Acids ◽  
Nuclear Localization ◽  
Simian Virus 40 ◽  
Simian Virus ◽  
T Antigen ◽  
Single Amino Acid ◽  
Nuclear Localization Sequence ◽  
Localization Sequence ◽  
Beta Galactosidase

Proteins destined for the nucleus contain nuclear localization sequences, short stretches of amino acids responsible for targeting them to the nucleus. We show that the first 29 amino acids of GAL4, a yeast DNA-binding protein, function efficiently as a nuclear localization sequence when fused to normally cytoplasmic invertase, but not when fused to Escherichia coli beta-galactosidase. Moreover, the nuclear localization sequence from simian virus 40 T antigen functions better when fused to invertase than when fused to beta-galactosidase. A single amino acid change in the T-antigen nuclear localization sequence inhibits the nuclear localization of simian virus 40-invertase and simian virus 40-beta-galactosidase in Saccharomyces cerevisiae. From these results, we conclude that the relative ability of a nuclear localization sequence to act depends on the protein to which it is linked.

scholarly journals Nuclear accumulation of p53 protein is mediated by several nuclear localization signals and plays a role in tumorigenesis.

1990 ◽  
Vol 10 (12) ◽  
pp. 6565-6577 ◽  
Author(s):  
G Shaulsky ◽  
N Goldfinger ◽  
A Ben-Ze'ev ◽  
V Rotter
Keyword(s):  
Nuclear Localization ◽  
Cell Nucleus ◽  
P53 Protein ◽  
Simian Virus 40 ◽  
T Antigen ◽  
Nuclear Accumulation ◽  
Mutant P53 ◽  
Wild Type ◽  
Nuclear Localization Signals ◽  
Wild Type P53

The basic carboxy terminus of p53 plays an important role in directing the protein into the nuclear compartment. The C terminus of the p53 molecule contains a cluster of several nuclear localization signals (NLSs) that mediate the migration of the protein into the cell nucleus. NLSI, the most active domain, is highly conserved in genetically diverged species and shares perfect homology with consensus NLS sequences found in other nuclear proteins. The other two NLSs, II and III, appear to be less effective and less conserved. Although nuclear localization is dictated primarily by the NLSs inherent in the primary amino acid sequence, the actual nuclear homing can be modified by interactions with other proteins expressed in the cell. Comparison between wild-type p53 and naturally occurring mutant p53 showed that both protein categories could migrate into the nucleus of rat primary embryonic fibroblasts by essentially similar mechanisms. Nuclear localization of both proteins was totally dependent on the existence of functional NLS domains. In COS cells, however, we found that NLS-deprived wild-type p53 molecules could migrate into the nucleus by complexing with another nuclear protein, simian virus 40 large-T antigen. Wild-type and mutant p53 proteins differentially complexed with viral or cellular proteins, which may significantly affect the ultimate compartmentalization of p53 in the cell; this finding suggests that the actual subcellular compartmentalization of proteins may differ in various cell type milieux and may largely be affected by the ability of these proteins to complex with other proteins expressed in the cell. Experiments designed to test the physiological significance of p53 subcellular localization indicated that nuclear localization of mutant p53 is essential for this protein to enhance the process of malignant transformation of partially transformed cells, suggesting that p53 functions within the cell nucleus.

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