FIGURE 5.

Replacing Arg⁸² and Arg⁹³ block the ability of PST to enhance the polysialylation of SW2 cell NCAM and the ability of PST H331K to inhibit the polysialylation of SW2 cell NCAM by endogenous enzyme. Myc-tagged PST, PST R82A/R93A, PST H331K, PST H331K R82A, PST H331K R93A, and PST H331K R82A/R93A were transiently expressed in SW2 small cell lung carcinoma cells. Eighteen hours post-transfection, cells were fixed and indirect immunofluorescence was performed to analyze enzyme localization (Myc, green, Enzyme localization) or total polysialylation (OL.28, red, Polysialylation). Cells expressing exogenous PST and PST mutant proteins are marked with yellow arrowheads. Cells were examined using a Zeiss 200M inverted confocal microscope, ×63 oil immersion objective. Scale bar = 10 μm.