An In Vitro Assay to Study Targeting of Membrane Proteins to the Inner Nuclear Membrane

Methods Mol Biol. 2016;1411:461-77. doi: 10.1007/978-1-4939-3530-7_28.


Newly synthesized membrane proteins are inserted into the endoplasmic reticulum (ER) from where they are constantly sorted to various cellular compartments. To analyze and visualize sorting of membrane proteins to the inner nuclear membrane (INM), we developed a trap-release system that uncouples membrane integration into the ER from transport. This assay allows the simultaneous release of a large pool of an INM-destined membrane protein from the ER and microscopy-based monitoring of targeting to the INM. The use of semi-permeabilized HeLa cells further enables the identification and characterization of essential requirements of the targeting process. This protocol provides a detailed description of reporter construction, in vitro reconstitution, and visualization of trafficking.

Keywords: In vitro reconstitution; Inner nuclear membrane; Membrane protein; Microscopy; Nuclear envelope; Semi-permeabilized cell system.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Line
  • Gene Expression
  • Gene Order
  • Genes, Reporter
  • HeLa Cells
  • Humans
  • Membrane Proteins / genetics
  • Membrane Proteins / isolation & purification
  • Membrane Proteins / metabolism*
  • Microscopy, Fluorescence
  • Nuclear Envelope / metabolism*
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / isolation & purification
  • Recombinant Fusion Proteins / metabolism
  • Time-Lapse Imaging


  • Membrane Proteins
  • Recombinant Fusion Proteins