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Related Concept Videos

Nuclear Localization Signals and Import01:46

Nuclear Localization Signals and Import

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...
Translocation of Proteins into the Mitochondria01:19

Translocation of Proteins into the Mitochondria

Mitochondrial precursors are translocated to the internal subcompartments via independent mechanisms involving distinct protein machineries called translocases.
Sorting of outer membrane proteins:
Mitochondrial outer membrane proteins are of two types: the transmembrane, beta-barrel porins, and the membrane-anchored, alpha-helical proteins. Beta-barrel porin precursors are translocated by the TOM complex and inserted into the outer mitochondrial membrane by the SAM complex. In contrast,...
Regulation of Nuclear Protein Sorting01:45

Regulation of Nuclear Protein Sorting

Nuclear protein sorting regulates nucleus composition and gene expression, crucial for determining the fate of a eukaryotic cell. Hence, the entry and exit of molecules across the nuclear envelope is a tightly controlled process. Nuclear protein sorting can be inhibited by one of the following ways: 1) masking cargo signal sequences, 2) modifying the nuclear receptor's affinity for cargo, 3) controlling the nuclear pore size, 4) retaining the cargo during its transit to the cytosol or the...
Caspases01:24

Caspases

Caspase, a family of cysteine proteases, serve as effectors in apoptosis. The ced3 gene in C.elegans was first identified to be involved in apoptosis. This gene encodes the ced-3 caspase that is similar to the interleukin-1-beta converting enzyme or ICE in mammals. In addition to apoptosis, caspases also function in the inflammatory response. Inflammatory caspases are essential in activating pro-inflammatory cytokines that recruit immune cells and block the replication of pathogens inside cells.
Nuclear Protein Sorting01:34

Nuclear Protein Sorting

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.
Proteins targeted to the nucleus carry nuclear localization signals or NLS recognized by import receptors in the cytosol. Similarly, proteins with nuclear export signals are recognized by export receptors. Import and export receptors are...
Nuclear Export01:42

Nuclear Export

The nucleus restricts several proteins within and allows others to pass. The restricted proteins possess a nuclear retention sequence or NRS, anchoring them to the nuclear lamins and preventing their transport to the cytosol. The non-restricted proteins, after their synthesis, are transported to their site of action, such as the cytosol or other organelles, with the help of nuclear export signals or NES.
NES are of three types- the canonical 10-residue long leucine-rich signal and other...

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Related Experiment Video

Updated: Jun 3, 2026

Reconstitution of Msp1 Extraction Activity with Fully Purified Components
05:52

Reconstitution of Msp1 Extraction Activity with Fully Purified Components

Published on: August 10, 2021

The importin-alpha/nucleophosmin switch controls taspase1 protease function.

Carolin Bier1, Shirley K Knauer, Dominic Docter

  • 1Molecular and Cellular Oncology/Mainz Screening Center, University Hospital of Mainz, Langenbeckstrasse 1, 55101 Mainz, Germany.

Traffic (Copenhagen, Denmark)
|March 23, 2011
PubMed
Summary
This summary is machine-generated.

Taspase1 protease localization and activity are regulated by a nuclear import signal and interaction with nucleophosmin. This mechanism controls Taspase1

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Strategies for Tracking Anastasis, A Cell Survival Phenomenon that Reverses Apoptosis
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Strategies for Tracking Anastasis, A Cell Survival Phenomenon that Reverses Apoptosis

Published on: February 16, 2015

Related Experiment Videos

Last Updated: Jun 3, 2026

Reconstitution of Msp1 Extraction Activity with Fully Purified Components
05:52

Reconstitution of Msp1 Extraction Activity with Fully Purified Components

Published on: August 10, 2021

Strategies for Tracking Anastasis, A Cell Survival Phenomenon that Reverses Apoptosis
12:55

Strategies for Tracking Anastasis, A Cell Survival Phenomenon that Reverses Apoptosis

Published on: February 16, 2015

Area of Science:

  • Molecular Biology
  • Cell Biology
  • Protease Function

Background:

  • Taspase1 is a threonine protease involved in processing key substrates like the mixed lineage leukemia protein.
  • Mechanisms governing Taspase1's intracellular localization and functional impact remain largely unknown.
  • Understanding Taspase1 regulation is crucial for elucidating its role in cellular processes.

Purpose of the Study:

  • To investigate the mechanisms controlling Taspase1's intracellular localization.
  • To determine the functional consequences of Taspase1 localization.
  • To elucidate the role of nucleophosmin in Taspase1 regulation.

Main Methods:

  • Analysis of endogenous and ectopically expressed Taspase1.
  • Microinjection and ectopic expression studies to identify nuclear import signals.
  • Interaction studies with importin-α and nucleophosmin.

Main Results:

  • Taspase1 is predominantly found in the nucleus, accumulating at the nucleolus.
  • A conserved bipartite nuclear import signal (NLS) mediates importin-α interaction and nuclear transport.
  • Nucleolar localization and catalytic activity depend on autoproteolytic processing and nucleophosmin binding.
  • Pathological nucleophosmin variants increase cytoplasmic Taspase1, facilitating cytoplasmic substrate cleavage.

Conclusions:

  • Taspase1's biological activity is regulated by a novel mechanism involving nuclear import and nucleophosmin interaction.
  • Nuclear import and nucleophosmin binding are essential for Taspase1's proteolytic activity and substrate processing.
  • Taspase1 utilizes nucleophosmin's export function for transient cytoplasmic access to cleave cytoplasmic substrates.