Enhanced EGFP-chromophore-assisted laser inactivation using deficient cells rescued with functional EGFP-fusion proteins

Proc Natl Acad Sci U S A. 2007 Apr 17;104(16):6702-7. doi: 10.1073/pnas.0701801104. Epub 2007 Apr 9.


Chromophore-assisted laser inactivation (CALI) is a light-mediated technique that offers precise spatiotemporal control of protein inactivation, enabling better understanding of the protein's role in cell function. EGFP has been used effectively as a CALI chromophore, and its cotranslational attachment to the target protein avoids having to use exogenously added labeling reagents. A potential drawback to EGFP-CALI is that the CALI phenotype can be obscured by the endogenous, unlabeled protein that is not susceptible to light inactivation. Performing EGFP-CALI experiments in deficient cells rescued with functional EGFP-fusion proteins permits more complete loss of function to be achieved. Here, we present a modified lentiviral system for rapid and efficient generation of knockdown cell lines complemented with physiological levels of EGFP-fusion proteins. We demonstrate that CALI of EGFP-CapZbeta increases uncapped actin filaments, resulting in enhanced filament growth and the formation of numerous protrusive structures. We show that these effects are completely dependent upon knocking down the endogenous protein. We also demonstrate that CALI of EGFP-Mena in Mena/VASP-deficient cells stabilizes lamellipodial protrusions.

Publication types

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

MeSH terms

  • Animals
  • Cell Line
  • Fluorescent Dyes / chemistry*
  • Green Fluorescent Proteins / genetics
  • Green Fluorescent Proteins / physiology*
  • Humans
  • Lasers*
  • Lentivirus
  • Rats
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / physiology*


  • Fluorescent Dyes
  • Recombinant Fusion Proteins
  • enhanced green fluorescent protein
  • Green Fluorescent Proteins