The nucleoporin Nup188 controls passage of membrane proteins across the nuclear pore complex

J Cell Biol. 2010 Jun 28;189(7):1129-42. doi: 10.1083/jcb.200912045. Epub 2010 Jun 21.

Abstract

All transport across the nuclear envelope (NE) is mediated by nuclear pore complexes (NPCs). Despite their enormous size, approximately 60 MD in vertebrates, they are comprised of only approximately 30 distinct proteins (nucleoporins or Nups), many of which form subcomplexes that act as building blocks for NPC assembly. One of these evolutionarily conserved subcomplexes, the Nup93 complex, is a major structural component linking the NPC to the membranes of the NE. Using in vitro nuclear assembly assays, we show that two components of the Nup93 complex, Nup188 and Nup205, are dispensable for NPC formation. However, nuclei lacking Nup188 increase in size by several fold compared with wild type. We demonstrate that this phenotype is caused by an accelerated translocation of integral membrane proteins through NPCs, suggesting that Nup188 confines the passage of membrane proteins and is thus crucial for the homeostasis of the different nuclear membranes.

MeSH terms

  • Active Transport, Cell Nucleus*
  • Animals
  • Cell Nucleus
  • Homeostasis
  • Membrane Proteins / metabolism*
  • Nuclear Envelope / metabolism
  • Nuclear Pore / metabolism*
  • Nuclear Pore Complex Proteins / metabolism
  • Nuclear Pore Complex Proteins / physiology*
  • Protein Transport
  • Xenopus
  • Xenopus Proteins / physiology*

Substances

  • Membrane Proteins
  • Nuclear Pore Complex Proteins
  • Nup188 protein, Xenopus
  • Nup93 protein, Xenopus
  • Xenopus Proteins