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. Author manuscript; available in PMC: 2013 Nov 1.
Published in final edited form as: Biochim Biophys Acta. 2012 Jul 3;1820(11):1734–1743. doi: 10.1016/j.bbagen.2012.06.020

Figure 1. Irradiation of endocytosed TMR-TAT kills cell while irradiation of microinjected TMR-TAT does not.

Figure 1

A) HeLa cells were incubated with TMR-TAT (3 μM), washed, and irradiated at 560 ± 20 nm through a 100 X objective on a wide-field microscope. The time displayed on the images represents the total light exposure time. The fluorescence signal of TMR-TAT (TMR channel) initially shows a punctate distribution consistent with the compound being present within endocytic organelles. Brief irradiation at 560 nm (TMR channel) causes TMR-TAT to redistribute throughout the cells. This is accompanied by blebbing of the plasma membrane (visible in the bright field image) and permeabilization of the plasma membrane, as seen by staining of the cells with SYTOX Blue. The TMR and SYTOX BLUE fluorescence signals are represented as inverted monochrome (black = fluorescent signal, white = no signal). B) TMR-TAT was microinjected into the cell and irradiated at 560 nm immediately. Irradiation had no apparent effect on the cells under conditions where the peptide is more concentrated inside cells and the light dose is more intense than in the incubated sample. Identical data were obtained with the protease resistant TMR-riTAT (not shown).