Coupling/pathway control diagrams illustrate the respiratory states obtained step-by-step in substrate-uncoupler-inhibitor titrations in a SUIT protocol. Each step (to the next state) is defined by an initial state and a metabolic control variable, X. The respiratory states are shown by boxes. X is usually the titrated substance in a SUIT protocol. If X (ADP, uncouplers, or inhibitors of the phosphorylation system, e.g. oligomycin) exerts coupling control, then a transition is induced between two coupling control states. If X (fuel substrates, e.g. pyruvate and succinate, or ET-pathway inhibitors, e.g. rotenone) exerts pathway control, then a transition is induced between two Electron transfer-pathway states. The type of metabolic control (X) is shown by arrows linking two respiratory states, with vertical arrows indicating coupling control, and horizontal arrows indicating pathway control. Marks define the section of an experimental trace in a given respiratory state (steady state). Events define the titration of X inducing a transition in the SUIT protocol. The specific sequence of coupling control and pathway control steps defines the SUIT protocol pattern. The coupling/pathway control diagrams define the categories of SUIT protocols (see Figure).
Reference: Gnaiger 2014 MitoPathways
Communicated by Gnaiger Erich 2016-06-07, edited 2016-10-31.