A protein-tagging system for signal amplification in gene expression and fluorescence imaging

Cell. 2014 Oct 23;159(3):635-46. doi: 10.1016/j.cell.2014.09.039. Epub 2014 Oct 9.


Signals in many biological processes can be amplified by recruiting multiple copies of regulatory proteins to a site of action. Harnessing this principle, we have developed a protein scaffold, a repeating peptide array termed SunTag, which can recruit multiple copies of an antibody-fusion protein. We show that the SunTag can recruit up to 24 copies of GFP, thereby enabling long-term imaging of single protein molecules in living cells. We also use the SunTag to create a potent synthetic transcription factor by recruiting multiple copies of a transcriptional activation domain to a nuclease-deficient CRISPR/Cas9 protein and demonstrate strong activation of endogenous gene expression and re-engineered cell behavior with this system. Thus, the SunTag provides a versatile platform for multimerizing proteins on a target protein scaffold and is likely to have many applications in imaging and controlling biological outputs.

Publication types

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

MeSH terms

  • Animals
  • CRISPR-Cas Systems
  • Genetic Techniques
  • Humans
  • Molecular Imaging / methods*
  • Optical Imaging / methods*
  • Protein Multimerization*
  • Proteins / chemistry*
  • Single-Chain Antibodies / chemistry


  • Proteins
  • Single-Chain Antibodies