Table II.

The tyrosine phosphorylation of Ad2 E4orf4 regulates its cytoplasmic membrane activity but not its nuclear activity

ConstructsC-33A293T293
NLApoptosisNLApoptosisNLApoptosis
% cells
24 h48 h48 h72 h24 h
GFP10849
GFP-NLS6954763411
GFP-CAAX<11113177
orf4-GFP29375635564237
3YF-GFP64214177132620
orf4-GFP-NLS65143494339221
3YF-GFP-NLS9217349130
orf4-GFPCAAX2395124248
3YF-GFPCAAX91316191410
n > 600n > 900n > 600n > 900n = 500n = 1,000
  • 293T, 293, and C-33A cells were transfected with the indicated GFP constructs; (3Y-F), nonphosphorylated mutant E4orf4. At the indicated times after transfection, cells were fixed and DNA was labeled with DAPI. Protein targeting efficiencies and apoptotic activities (nuclear condensation and fragmentation) were evaluated by fluorescence microscopy and are expressed as the percentage of nuclear localization (NL), or the percentage of apoptosis, relative to the total number of GFP-positive cells. Data are the means ± SE of four independent experiments.