Fig. 2.

Inhibition of de novo CTP synthesis promotes IMPDH cytoophidium assembly. (A–E) Immunofluorescence of HEK 293T cells treated with 100 μM DAU for 0, 0.5, 1, 2 and 4 h. Scale bars: 20 μm. (F) Mean±s.e.m. percentages of cells with IMPDH cytoophidia. Lowercase letters represent significant differences between groups (one-way ANOVA with Tukey's test). (G) Ratios of mature and immature IMPDH cytoophidia observed in cells cultured in 100 μM DAU for different durations. (H) Nucleotide levels in cells treated with 100 μM DAU for different durations. Nucleotide concentrations for each point were normalized to the level of ATP. (I) The changes of GTP concentration within 1 h intervals shows that intracellular GTP accumulates faster in the first hour than later few hours of DAU treatment.