Laser fluorescence microscopy of nuclear protein targeting by synthetic signal peptides

Immunoglobulin G was conjugated with synthetic peptides containing the nuclear localization sequence of the simian virus 40 T-antigen. The peptide-protein conjugates were injected into the cytoplasm of hepatoma cells. Nucleocytoplasmic transport of the conjugates was studied by both immunofluorescence staining of fixed cells and laser microfluorimetry of living cells. The results obtained by the two methods were compared and discussed with regard to previous studies of nucleocytoplasmic protein transport.