Fig. 3
Time-resolved data informs pathway directionality. A schematic model for the interpretation of time course data. The observed time courses of the levels of A, B, and C, which are known to belong to the same linear pathway reveal the order of the three components in the pathway and the direction of the flux through the pathway. A, B, and C can be metabolites in a metabolic pathway, phosphorylated proteins in a kinase cascade, or members of any other matter- or signal-transducing pathway. The component D, for which the network connection to the ABC pathway is unknown, cannot be upstream of A, and it cannot be downstream of C. This information can be valuable in validating hypotheses on the network connection of D