The reference state, Z, is the respiratory state with high flux in relation to the background state, Y. The transition between the background state and the reference state is a step brought about by a metabolic control variable, X. If X stimulates flux (ADP, fuel substrate), it is present in the reference state but absent in the background state. If X is an inhibitor of flux, it is absent in the reference state but present in the background state. The reference state is specific for a single step to define the flux control factor. In contrast, in a sequence of multiple steps, the common reference state is frequently taken as the state with the highest flux in the entire sequence, as used in the definition of the flux control ratio.
MitoPedia topics: EAGLE
Communicated by Gnaiger E 2013-08-01; edited 2016-11-19.