Making water-soluble integral membrane proteins in vivo using an amphipathic protein fusion strategy

Nat Commun. 2015 Apr 8;6:6826. doi: 10.1038/ncomms7826.


Integral membrane proteins (IMPs) play crucial roles in all cells and represent attractive pharmacological targets. However, functional and structural studies of IMPs are hindered by their hydrophobic nature and the fact that they are generally unstable following extraction from their native membrane environment using detergents. Here we devise a general strategy for in vivo solubilization of IMPs in structurally relevant conformations without the need for detergents or mutations to the IMP itself, as an alternative to extraction and in vitro solubilization. This technique, called SIMPLEx (solubilization of IMPs with high levels of expression), allows the direct expression of soluble products in living cells by simply fusing an IMP target with truncated apolipoprotein A-I, which serves as an amphipathic proteic 'shield' that sequesters the IMP from water and promotes its solubilization.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Antigens, Surface / chemistry
  • Antigens, Surface / metabolism*
  • Antiporters / chemistry
  • Antiporters / metabolism*
  • Apolipoprotein A-I / chemistry
  • Apolipoprotein A-I / metabolism*
  • Bacterial Outer Membrane Proteins / chemistry
  • Bacterial Outer Membrane Proteins / metabolism*
  • Bacterial Vaccines / chemistry
  • Bacterial Vaccines / metabolism*
  • Borrelia burgdorferi
  • Escherichia coli
  • Escherichia coli Proteins / chemistry
  • Escherichia coli Proteins / metabolism*
  • Hydrophobic and Hydrophilic Interactions*
  • Lipoproteins / chemistry
  • Lipoproteins / metabolism*
  • Membrane Proteins / chemistry
  • Membrane Proteins / metabolism*
  • Solubility


  • Antigens, Surface
  • Antiporters
  • Apolipoprotein A-I
  • Bacterial Outer Membrane Proteins
  • Bacterial Vaccines
  • Escherichia coli Proteins
  • Lipoproteins
  • Membrane Proteins
  • OspA protein
  • EmrE protein, E coli