A classical NLS and the SUN domain contribute to the targeting of SUN2 to the inner nuclear membrane

EMBO J. 2010 Jul 21;29(14):2262-75. doi: 10.1038/emboj.2010.119. Epub 2010 Jun 15.

Abstract

Integral membrane proteins of the inner nuclear membrane (INM) are inserted into the endoplasmic reticulum membrane during their biogenesis and are then targeted to their final destination. We have used human SUN2 to delineate features that are required for INM targeting and have identified multiple elements that collectively contribute to the efficient localization of SUN2 to the nuclear envelope (NE). One such targeting element is a classical nuclear localization signal (cNLS) present in the N-terminal, nucleoplasmic domain of SUN2. A second motif proximal to the cNLS is a cluster of arginines that serves coatomer-mediated retrieval of SUN2 from the Golgi. Unexpectedly, also the C-terminal, lumenal SUN domain of SUN2 supports NE localization, showing that targeting elements are not limited to cytoplasmic or transmembrane domains of INM proteins. Together, SUN2 represents the first mammalian INM protein relying on a functional cNLS, a Golgi retrieval signal and a perinuclear domain to mediate targeting to the INM.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Endoplasmic Reticulum / metabolism
  • HeLa Cells
  • Humans
  • Intracellular Signaling Peptides and Proteins / chemistry
  • Intracellular Signaling Peptides and Proteins / genetics*
  • Intracellular Signaling Peptides and Proteins / metabolism*
  • Karyopherins / chemistry
  • Karyopherins / metabolism
  • Membrane Proteins / chemistry
  • Membrane Proteins / genetics*
  • Membrane Proteins / metabolism*
  • Nuclear Envelope / genetics
  • Nuclear Envelope / metabolism*
  • Nuclear Localization Signals*
  • Protein Binding
  • Recombinant Fusion Proteins / chemistry
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / metabolism

Substances

  • Intracellular Signaling Peptides and Proteins
  • Karyopherins
  • Membrane Proteins
  • Nuclear Localization Signals
  • Recombinant Fusion Proteins
  • SUN2 protein, human