Dynamics of proteasome distribution in living cells

Eric A.J. Reits, Adam M. Benham, Beatrice Plougastel, Jacques Neefjes, John Trowsdale

Research output: Contribution to journalArticle

229 Scopus citations

Abstract

Proteasomes are proteolytic complexes involved in non-lysosomal degradation which are localized in both the cytoplasm and the nucleus. The dynamics of proteasomes in living cells is unclear, as is their targeting to proteins destined for degradation. To investigate the intracellular distribution and mobility of proteasomes in vivo, we generated a fusion protein of the proteasome subunit LMP2 and the green fluorescent protein (GFP). The LMP2-GFP chimera was quantitatively incorporated into catalytically active proteasomes. The GFP-tagged proteasomes were located within both the cytoplasm and the nucleus. Within these two compartments, proteasomes diffused rapidly, and bleaching experiments demonstrated that proteasomes were transported slowly and unidirectionally from the cytoplasm into the nucleus. During mitosis, when the nuclear envelope has disintegrated, proteasomes diffused rapidly throughout the dividing cell without encountering a selective barrier. Immediately after cell division, the restored nuclear envelope formed a new barrier for the diffusing proteasomes. Thus, proteasomes can be transported unidirectionally over the nuclear membrane, but can also enter the nucleus upon reassembly during cell division. Since proteasomes diffuse rapidly in the cytoplasm and nucleus, they may perform quality control by continuous collision with intracellular proteins, and degrading those proteins that are properly tagged or misfolded.

Original languageEnglish
Pages (from-to)6087-6094
Number of pages8
JournalEMBO Journal
Volume16
Issue number20
DOIs
StatePublished - Nov 5 1997
Externally publishedYes

Keywords

  • Antigen presentation
  • GFP
  • Nuclear import
  • Photobleaching
  • Proteasome

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    Reits, E. A. J., Benham, A. M., Plougastel, B., Neefjes, J., & Trowsdale, J. (1997). Dynamics of proteasome distribution in living cells. EMBO Journal, 16(20), 6087-6094. https://doi.org/10.1093/emboj/16.20.6087