Figure 1.

Switching of protein sialylation in ST3Gal IV expressing gastric carcinoma cells leading to SLe^x expression. A - Periodic Acid-Schiff (PAS) staining of SDS-PAGE glycoproteins from Mock and MST3Gal IV total cell lysates showed no differences in total cell protein glycosylation on both cell lines; Horseradish peroxidase was used as positive staining control; Arrows 1 and 2 indicate the bands selected for protein identification by MALDI-TOF/TOF mass spectrometry. B - Evaluation of α2-6 and α2-3 linked NeuAc by SNA, MAL I and MAL II lectin staining on Mock and MST3Gal IV cells. Results showed a reduce intensity of α2-6 linked NeuAc carrying glycans accompanied by an increase in α2-3 linked NeuAc at high molecular weight protein in ST3Gal IV expressing cells. Mackia ammorensis lectins, capable of recognizing different α2-3 linked NeuAc carrying glycans structures, further demonstrated the presence of α2-3 linked NeuAc in Galβ1-4GlcNAc structures; C - Western blot analysis of SLe^X structures using two different antibodies showed the presence of SLe^x antigens on high molecular weight proteins from ST3Gal IV expressing cells with no expression on Mock control cells.