Site-specific covalent labeling of proteins inside live cells using small molecule probes

Bioorg Med Chem. 2009 Feb 1;17(3):981-9. doi: 10.1016/j.bmc.2008.01.043. Epub 2008 Jan 30.


The study of dynamic movement and interactions of proteins inside living cells in real time is critical for a better understanding of cellular mechanisms and functions in molecular detail. Genetically encoded fusions to fluorescent protein(s) (FP) have been widely used for this purpose [Annu. Rev. Biochem. 1998, 67, 509-544]. To obviate some of the drawbacks associated with the use of FPs [Curr. Opin. Biotechnol. 2005, 16, 1-6; Nat. Methods2006, 3, 591-596], we report a small molecule-based approach that exploits the unique reactivity between the cysteine residue at the N-terminus of a target protein and cell-permeable, thioester-based small molecule probes resulting in site-specific, covalent tagging of proteins. This approach has been demonstrated by the in vivo labeling of proteins in both bacterial and mammalian systems thereby making it potentially useful for future bioimaging applications.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Line
  • Cysteine / chemistry
  • Fluorescence Resonance Energy Transfer
  • Fluorescent Dyes / chemistry
  • Humans
  • Inteins
  • Microscopy, Fluorescence
  • Molecular Probes / chemistry*
  • Molecular Probes / metabolism
  • Recombinant Fusion Proteins / analysis*
  • Recombinant Fusion Proteins / chemistry
  • Recombinant Fusion Proteins / metabolism


  • Fluorescent Dyes
  • Molecular Probes
  • Recombinant Fusion Proteins
  • Cysteine