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Related Concept Videos

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Nuclear Localization Signals and Import

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Proteins targeted to the nucleus carry short stretches of amino acid sequences called the nuclear localization signal or NLS. Classical nuclear localization signals are of two types: monopartite and bipartite NLS. Monopartite classical NLS (cNLS) consists of a single cluster of 4-8 amino acids. Bipartite cNLS consists of two clusters of  2-3 amino acids and a 9-12 residue long proline-rich linker bridging the two clusters. Signal clusters are rich in positively charged amino acids such as...
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Mitochondria, chloroplasts, and gram-negative bacteria have transmembrane, beta-barrel proteins called porins to mediate the free diffusion of ions and metabolites across the membrane. Mitochondrial porin precursors contain conserved amino acid sequences called beta signals at their C-terminal. Beta signals have a  motif of PoXGXXHyXHy (Po-Polar, X-Any amino acid, G-Glycine, Hy-LargeHydrophobic), which are crucial for precursor recognition to initiate precursor assembly. Beta-barrel...
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Mitochondrial precursors are translocated to the internal subcompartments via independent mechanisms involving distinct protein machineries called translocases.
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Mitochondrial Precursor Proteins01:39

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Mitochondrial precursors are partially unfolded or loosely folded polypeptide chains. Newly synthesized precursors are inhibited from spontaneously folding into their native conformation by the cytosolic chaperones, heat shock proteins 70 (Hsp70), and mitochondrial import stimulation factors (MSFs). Precursors bound to MSFs are guided to the TOM70-TOM37 receptors, while precursors bound to Hsp70  chaperones are targetted to TOM20-TOM22 receptor complexes.
Most of the mitochondrial...
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Mitochondria are double-membrane organelles of the eukaryotes involved in cellular metabolism, signaling, ATP synthesis, and programmed cell death.  Each of these processes requires specific proteins and enzymes that must be correctly sorted to the right mitochondrial subcompartment for the proper functioning of the organelle.
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Nuclear Protein Sorting01:34

Nuclear Protein Sorting

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Nuclear protein sorting is the selective trafficking of histones, polymerases, gene regulatory proteins into the nucleus and exporting RNAs and ribosomes to the cytosol. It is a tightly controlled process that regulates gene expression within a cell.
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Data on dimer formation between importin α subtypes.

Yoichi Miyamoto1, Masahiro Oka1

  • 1Laboratory of Nuclear Transport Dynamics, National Institutes of Biomedical Innovation, Health and Nutrition, 7-6-8 Saito-Asagi, Ibaraki, Osaka 567-0085, Japan.

Data in Brief
|May 26, 2016
PubMed
Summary

Importin alpha8, a nuclear localization signal receptor, forms dimers with other importins. It also releases nuclear proteins from importin alpha3, suggesting a role in nuclear transport regulation.

Keywords:
DimerImportin αNuclear localization signalNuclear transport

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Area of Science:

  • Cell biology
  • Molecular biology
  • Protein-protein interactions

Background:

  • Importins are key regulators of nuclear transport.
  • Classical nuclear localization signals (cNLS) mediate protein import into the nucleus.
  • Importin alpha proteins function as cNLS receptors.

Purpose of the Study:

  • To functionally characterize importin alpha8 (Impα8) as a cNLS receptor.
  • To investigate the dimerization capabilities of Impα8.
  • To determine the effect of Impα8 on cNLS substrate release from other importins.

Main Methods:

  • GST pull-down assays were used to assess protein-protein interactions.
  • Dimerization between importin alpha family members was analyzed.
  • The release of cNLS substrates (SV40T NLS, p53) from importin alpha3 (Impα3) was monitored.

Main Results:

  • Both Impα1 and Impα8 dimerize with Impα6, Impα7, and Impα8.
  • Impα8 exhibits a higher dimerization ability compared to Impα1.
  • Impα1 or Impα8 can form heterodimers with Impα3, leading to the release of cNLS substrates like SV40T NLS and p53.

Conclusions:

  • Importin alpha8 is a functional cNLS receptor with significant dimerization potential.
  • Impα8's ability to displace substrates from Impα3 suggests a regulatory role in nuclear import.
  • These findings provide insights into the complex mechanisms governing nuclear transport.