Supplementary Figure 2: The His129 and Pro129 variants of hGPT are active and have comparable specific activity.

a, TLC plate image of hGPT His129- and Pro129-catalyzed reactions (in triplicate) containing 200 nM of each enzyme, 500 μM C55-dol-P, 0.1 mM UDP-GlcNAc and 0.01 mM [14C]UDP-GlcNAc, 70 mM Tris-HCl pH 8.0, 500 mM NaCl, 80 mM MgCl2, 5 mM DM, 1 mg/mL POPG, and 10% glycerol. A time course assay was conducted at 30°C and 2 μL of each reaction was spotted on the TLC plate every 5 min; the 15 min time point shown is within the linear range. b, Specific activity measurements based on spot intensity quantification of the substrate and product bands shown in panel a. Three technical replicates are shown, with the mean value represented by a line.