FIGURE 2.

Expression of the murine Neu4 sialidase. a, immunoblotting of the two isoforms of the HA-tagged Neu4 protein. Expression plasmids encoding HA-tagged Neu4a and Neu4b were transfected into HEK293T cells, and homogenates were subjected to SDS-PAGE and immunoblotted with anti-HA antibody. Transfection efficiency was adjusted using the luciferase vector as a control. Bands for 55 kDa and 53.5 kDa were obtained for Neu4a and Neu4b, respectively. b, sialidase activity in the transfected cells using GD3 as the substrate. c, substrate specificity of Neu4b expressed in HEK293T cells. Sialidase activity toward various sialic acid-containing glycoconjugates was examined using cell homogenates. d, PSA-NCAM change in Neu4-transfected cells. Neuro2a cells were co-transfected with ST8siaIV and Neu4 genes. PSA-NCAM, NCAM, and tubulin were assessed by immunoblotting.