Functional expression of a two-transmembrane HtrII protein using cell-free synthesis

Yuki Sudo, Rikou Tanaka, Toshitatsu Kobayashi, Naoki Kamo, Toshiyuki Kohno, Chojiro Kojima

Research output: Contribution to journalArticlepeer-review


An approach of cell-free synthesis is presented for the functional expression of transmembrane proteins without the need of refolding. The transmembrane region of the pharaonis halobacterial transducer protein, pHtrII, was translated with various large soluble tags added (thioredoxin, glutathione S-transferase, green fluorescent protein and maltose binding protein). In this system, all fusion pHtrII were translated in a soluble fraction, presumably, forming giant micelle-like structures. The detergent n-dodecyl-β-D-maltoside was added for enhancing the solubilization of the hydrophobic region of pHtrII. The activity of the expressed pHtrII, having various tags, was checked using a pull-down assay, using the fact that pHtrII forms a signaling complex with pharaonis phoborhodopsin (ppR) in the membrane, as also in the presence of a detergent. All tagged pHtrII showed a binding activity with ppR. Interestingly, the binding activity with ppR was positively correlated with the molecular weight of the soluble tags. Thus, larger soluble tags lead to higher binding activities. We couldshow, that our approach is beneficial for the preparation of active membrane proteins, and is also potentially applicable for larger membrane proteins, such as 7- transmembrane proteins.

Original languageEnglish
Pages (from-to)51-58
Number of pages8
Publication statusPublished - 2011
Externally publishedYes


  • Cell-free protein synthesis
  • Membrane protein
  • Protein-protein interaction
  • Sensory rhodopsin

ASJC Scopus subject areas

  • Biophysics


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