Template:SUIT-034 O2 mt D111

Steps and respiratory states

Step	State	Pathway	Q-junction	Comment - Events (E) and Marks (M)
mt	REN			mt Respiration in the REN state is due to the presence of residual endogenous substrates.
1D.1				mt;1D.1 The addition of a low concentration of ADP (0.1 μM) stimulates the consumption of endogenous substrates, which can be observed as a decrease in respiration.
2PGM	PGM	N	CI	mt;1D.1;2PGM NADH-linked substrates (type N-pathway to Q). The addition of fuel substrates may trigger a transient peak increase in mitochondrial respiration due to the presence of low ADP concentrations. Once ADP is phosphorylated to ATP the respiration decreases. In the presence of ATPases in the sample, ATP is recycled to ADP, making it not possible to measure LEAK state.
3D2.5	PGM_P	N	CI	mt;1D.1;2PGM;3D2.5 NADH-linked substrates (type N-pathway to Q). OXPHOS capacity P (with saturating [ADP]), active OXPHOS state.
4U	PGM_E	N	CI	mt;1D.1;2PGM;3D2.5;4U NADH-linked substrates (type N-pathway to Q). Uncoupler titration (avoiding inhibition by high uncoupler concentrations) to obtain electron transfer (ET) capacity E (noncoupled ET-state). Test for limitation of OXPHOS capacity P by the phosphorylation system (ANT, ATP synthase, phosphate transporter) relative to ET capacity E in mt-preparations: E-P control efficiency and E-L coupling efficiency. In living cells: E-R control efficiency and E-L coupling efficiency.
5Myx	ROX	N	CI	mt;1D.1;2PGM;3D2.5;4U;5Myx Rox is the residual oxygen consumption in the ROX state, due to oxidative side reactions, estimated after addition of myxothiazol (inhibitor of CIII). Rox is subtracted from oxygen flux as a baseline for all respiratory states, to obtain mitochondrial respiration (mt).