scholarly journals Endogenous axoplasmic proteins and proteins containing nuclear localization signal sequences use the retrograde axonal transport/nuclear import pathway in Aplysia neurons

1993 ◽  
Vol 13 (9) ◽  
pp. 4064-4071 ◽  
Author(s):  
R Schmied ◽  
CC Huang ◽  
XP Zhang ◽  
DA Ambron ◽  
RT Ambron
Keyword(s):  
Axonal Transport ◽  
Nuclear Localization ◽  
Nuclear Import ◽  
Nuclear Localization Signal ◽  
Retrograde Axonal Transport ◽  
Signal Sequences ◽  
Aplysia Neurons ◽  
Localization Signal

Nuclear import of glycoconjugates is distinct from the classical NLS pathway

1995 ◽  
Vol 108 (4) ◽  
pp. 1325-1332 ◽  
Author(s):  
E. Duverger ◽  
C. Pellerin-Mendes ◽  
R. Mayer ◽  
A.C. Roche ◽  
M. Monsigny
Keyword(s):  
Nuclear Localization ◽  
Nuclear Import ◽  
Nuclear Localization Signal ◽  
Peptide Sequence ◽  
Nuclear Pore ◽  
Dependent Manner ◽  
Permeabilized Cells ◽  
Localization Signal ◽  
Energy Dependent ◽  
Cytosolic Factors

The nuclear import of many proteins depends on a short peptide sequence called the nuclear localization signal. However, glycosylated proteins, which lack such a nuclear localization signal, upon their injection into the cytosol by electroporation, enter the nucleus in a sugar-dependent manner. This paper brings new insights on the mechanism of this process, based on a study of neoglycoprotein nuclear uptake by digitonin-permeabilized cells. The nuclear import of neoglycoproteins is energy dependent: it does not occur when cells are maintained at 4 degrees C or when cells are ATP-depleted by treatment with apyrase. The nuclear import of neoglycoproteins occurs through the nuclear pore: it is inhibited by preincubation of cells with wheat germ agglutinin, a lectin which binds the nuclear pore glycoproteins and blocks the translocation step of nuclear localization signal bearing proteins through the nuclear pore. Furthermore, the nuclear import of neoglycoproteins does not use the pathway of nuclear localization signal bearing proteins: nuclear import of nuclear localization signal bearing proteins depends on cytosolic factors and is inhibited by treatment of cells with N-ethylmaleimide, while the nuclear import of neoglycoproteins neither requires added cytosolic factors nor is sensitive to alkylation by N-ethylmaleimide. In addition, upon incubation in the presence of a large excess of nuclear localization signal bearing protein, the nuclear import of neoglycoproteins is not inhibited.

Nuclear transport of the U2 snRNP-specific U2B'' protein is mediated by both direct and indirect signalling mechanisms

1994 ◽  
Vol 107 (7) ◽  
pp. 1807-1816 ◽  
Author(s):  
C. Kambach ◽  
I.W. Mattaj
Keyword(s):  
Nuclear Localization ◽  
Nuclear Import ◽  
Nuclear Localization Signal ◽  
Nuclear Transport ◽  
U2 Snrna ◽  
Central Segment ◽  
U2 Snrnp ◽  
U1 Snrnp ◽  
Localization Signal ◽  
Protein Amino Acids

Experiments investigating the nuclear import of the U2 snRNP-specific B'' protein (U2B'') are presented. U2B'' nuclear transport is shown to be able to occur independently of binding to U2 snRNA. The central segment of the protein (amino acids 90–146) encodes an unusual nuclear localization signal (NLS) that is related to that of the U1 snRNP-specific A protein. However, nuclear import of U2B'' does not depend on this NLS. Sequences in the N-terminal RNP motif of the protein are sufficient to direct nuclear transport, and evidence is presented that the interaction of U2B'' with the U2A' protein mediates this effect. This suggests that U2B'' can ‘piggy-back’ to the nucleus in association with U2A’, and thus be imported to the nucleus by two different mechanisms. U2A' nuclear transport, on the other hand, can occur independently of both U2B'' binding and of U2 snRNA.

scholarly journals Mechanisms Directing the Nuclear Localization of the CtBP Family Proteins

2006 ◽  
Vol 26 (13) ◽  
pp. 4882-4894 ◽  
Author(s):  
Alexis Verger ◽  
Kate G. R. Quinlan ◽  
Linda A. Crofts ◽  
Stefania Spanò ◽  
Daniela Corda ◽  
...  
Keyword(s):  
Nuclear Localization ◽  
Nuclear Import ◽  
Nuclear Localization Signal ◽  
Transcriptional Repression ◽  
Intracellular Trafficking ◽  
Nuclear Accumulation ◽  
Splice Isoforms ◽  
Localization Signal ◽  
Splice Isoform ◽  
Partner Proteins

ABSTRACT The C-terminal binding protein (CtBP) family includes four proteins (CtBP1 [CtBP1-L], CtBP3/BARS [CtBP1-S], CtBP2, and RIBEYE) which are implicated both in transcriptional repression and in intracellular trafficking. However, the precise mechanisms by which different CtBP proteins are targeted to different subcellular regions remains unknown. Here, we report that the nuclear import of the various CtBP proteins and splice isoforms is differentially regulated. We show that CtBP2 contains a unique nuclear localization signal (NLS) located within its N-terminal region, which contributes to its nuclear accumulation. Using heterokaryon assays, we show that CtBP2 is capable of shuttling between the nucleus and cytoplasm of the cell. Moreover, CtBP2 can heterodimerize with CtBP1-L and CtBP1-S and direct them to the nucleus. This effect strongly depends on the CtBP2 NLS. PXDLS motif-containing transcription factors, such as BKLF, that bind CtBP proteins can also direct them to the nucleus. We also report the identification of a splice isoform of CtBP2, CtBP2-S, that lacks the N-terminal NLS and localizes to the cytoplasm. Finally, we show that mutation of the CtBP NADH binding site impairs the ability of the proteins to dimerize and to associate with BKLF. This reduces the nuclear accumulation of CtBP1. Our results suggest a model in which the nuclear localization of CtBP proteins is influenced by the CtBP2 NLS, by binding to PXDLS motif partner proteins, and through the effect of NADH on CtBP dimerization.

scholarly journals Nuclear Localization Signal and Protein Context both Mediate Importin α Specificity of Nuclear Import Substrates

2006 ◽  
Vol 26 (23) ◽  
pp. 8697-8709 ◽  
Author(s):  
Beate Friedrich ◽  
Christina Quensel ◽  
Thomas Sommer ◽  
Enno Hartmann ◽  
Matthias Köhler
Keyword(s):  
Nuclear Localization ◽  
Nuclear Import ◽  
Nuclear Localization Signal ◽  
Protein Import ◽  
Binding Studies ◽  
Vitro Binding ◽  
Importin Α ◽  
Localization Signal ◽  
Experimental Approaches

ABSTRACT The “classical” nuclear protein import pathway depends on importin α and importin β. Importin α binds nuclear localization signal (NLS)-bearing proteins and functions as an adapter to access the importin β-dependent import pathway. In humans, only one importin β is known to interact with importin α, while six α importins have been described. Various experimental approaches provided evidence that several substrates are transported specifically by particular α importins. Whether the NLS is sufficient to mediate importin α specificity is unclear. To address this question, we exchanged the NLSs of two well-characterized import substrates, the seven-bladed propeller protein RCC1, preferentially transported into the nucleus by importin α3, and the less specifically imported substrate nucleoplasmin. In vitro binding studies and nuclear import assays revealed that both NLS and protein context contribute to the specificity of importin α binding and transport.

Sign in / Sign up

Export Citation Format

Share Document