Figure 1

The reaction-based specification of the model according to the notation introduced in Gostner et al.61. Rectangles identify model variables, non-boxed substrates are model constants, green circles identify enzymes, dark blue arcs identify matter transformation, and light blue arcs identify regulatory events (dotted lines indicate activations and solid lines indicate inhibitions). The purple boxes indicate reactions and variables associated with the folate cycle and the homocysteine remethylation cycle, respectively.