Azido-metabolic labeling of <i>C. elegans</i> cells generates glycoprotein candidates.

<p><i>C. elegans</i> embryonic cells grown with 40 µM azido-GalNAc (top panels) or 40 µM GalNAc (bottom panels) were reacted with TAMRA-alkyne and fractionated by 2DE. (A), (B), and (C) each show a different field of view representative of two independent experiments. Within each field of view, metabolically labeled glycoproteins were detected in-gel by their TAMRA fluorescence (left panels). And subsequently, the total protein profile of the sample was visualized with Sypro protein stain (right panels). Arrowheads mark glycoprotein candidates that met the criteria listed in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0049020#s2" target="_blank">Results and Discussion</a>. Some spots marked with arrowheads were cut from the gels shown while others were cut from the gels of the other independent experiment. MALDI-TOF/TOF identified the following <i>C. elegans</i> proteins within each arrowhead-marked spot: (a) ATP synthase α-subunit (H28O16.1); (b) Acyl CoA Dehydrogenase family member (<i>acdh-12</i>); (c) Ubiquinol-Cytochrome c oxidoreductase complex family member (<i>ucr-2.3</i>); (d) Actin (peptides shared by ACT-2, ACT-3, and ACT-4 were observed); (e) TCTP (translationally-controlled tumor protein) homolog family member (<i>tct-1</i>); (f) Aspartyl protease family member (<i>asp-4</i>); (g) Tubulin, Beta family member (<i>tbb-1</i>); (h) Tubulin, Beta family member (<i>tbb-1</i>). TBB-1 was found in two different 2DE spots likely due to post-translational modification or proteolytic processing.