An Improved Strategy for Fluorescent Tagging of Membrane Proteins for Overexpression and Purification in Mammalian Cells

Biochemistry. 2018 Dec 11;57(49):6741-6751. doi: 10.1021/acs.biochem.8b01070. Epub 2018 Nov 27.

Abstract

An essential prerequisite for in vitro biochemical or structural studies is a construct that is amenable to high level expression and purification and is biochemically "well-behaved". In the field of membrane protein research, the use of green fluorescent protein (GFP) to monitor and optimize the heterologous expression in different hosts has radically changed the ease of streamlining and multiplexing the testing of a large number of candidate constructs. This is achieved by genetically fusing the fluorescent proteins to the N- or C-terminus of the proteins of interest to act as reporters which can then be followed by methods such as microscopy, spectroscopy, or in-gel fluorescence. Nonetheless, a systematic study on the effect of GFP and its spectral variants on the expression and yields of recombinant membrane proteins is lacking. In this study, we genetically appended four common fluorescent protein tags, namely, mEGFP, mVenus, mCerulean, and mCherry, to the N- or C-terminus of different membrane proteins and assessed their expression in mammalian cells by fluorescence-detection size exclusion chromatography (FSEC) and protein purification. We find that, of the four fluorescent proteins, tagging with mVenus systematically results in higher expression levels that translates to higher yields in preparative purifications, thus making a case for switching to this yellow spectral variant as a better fusion tag.

Publication types

  • Research Support, N.I.H., Intramural

MeSH terms

  • Acyltransferases / chemistry
  • Acyltransferases / genetics
  • Acyltransferases / metabolism
  • Bacterial Proteins / chemistry
  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism
  • Chloride Channels / chemistry
  • Chloride Channels / genetics
  • Chloride Channels / metabolism
  • Gene Expression
  • Green Fluorescent Proteins / chemistry
  • Green Fluorescent Proteins / genetics
  • Green Fluorescent Proteins / metabolism
  • HEK293 Cells
  • Humans
  • Luminescent Proteins / chemistry
  • Luminescent Proteins / genetics
  • Luminescent Proteins / metabolism*
  • Membrane Proteins / chemistry
  • Membrane Proteins / genetics
  • Membrane Proteins / metabolism*
  • Microscopy, Confocal
  • Protein Stability
  • Recombinant Fusion Proteins / chemistry
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / metabolism*
  • Red Fluorescent Protein
  • Transduction, Genetic
  • Transfection

Substances

  • Bacterial Proteins
  • Chloride Channels
  • Luminescent Proteins
  • Membrane Proteins
  • Recombinant Fusion Proteins
  • enhanced green fluorescent protein
  • yellow fluorescent protein, Bacteria
  • Green Fluorescent Proteins
  • Acyltransferases
  • ZDHHC20 protein, human
  • PORCN protein, human