PM pathway control state

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Bioblasts - Richard Altmann and MiPArt by Odra Noel
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MitoPedia

PM pathway control state

Description

PM
PM: Pyruvate & Malate.

MitoPathway control state: N

SUIT protocol: 1PM;2D;3U;4G;5S;6Oct;7Rot;8Gp- - SUIT_RP1

Pyruvate (P) is oxidatively decarboxylated to acetyl-CoA and CO2, yielding NADH catalyzed by pyruvate dehydrogenase. Malate (M) is oxidized to oxaloacetate by mt-malate dehydrogenase located in the mitochondrial matrix. Condensation of oxaloacate with acetyl-CoA yields citrate (citrate synthase). 2-oxoglutarate (α-ketoglutarate) is formed from isocitrate (isocitrate dehydrogenase).

Abbreviation: PM

Reference: Gnaiger 2014 MitoPathways - Chapter 3.2


MitoPedia concepts: SUIT state 

Gnaiger 2014 MitoPathways - Chapter 3.2

PML

LEAK state (L) with PM as N-linked substrates can be evaluated in the following SUIT protocols:


PMP

OXPHOS state (P) with PM as N-linked substrates can be evaluated in the following SUIT protocols:

PME

ET state (E) with PM as N-linked substrates can be evaluated in the following SUIT protocols:


Linear coupling control in the N-pathway control state: L – P - E

  • L - P
OXPHOS coupling efficiency (P-L or ≈P control factor), j≈P = ≈P/P = (P-L)/P = 1-L/P, is measured in the CI-linked substrate state, with defined coupling sites (CI, CIII, CIV) and at high flux.
  • P - E
CCCP is titrated stepwise to maximum flux, to evaluate limitation of OXPHOS by the phosphorylation system, expressed as the apparent excess E-P capacity factor (E-P coupling control factor), jExP = (E-P)/E = 1-P/E. If jExP>0, then the ET-coupling efficiency rather than the OXPHOS coupling efficiency is the proper expression of coupling, j≈E = ≈E/E = (E-L)/E = 1-L/E.


Discussion

The Pyruvate anaplerotic pathway control state (pyruvate alone) is not an ET-pathway competent substrate state in most mt-preparations, since acetyl-CoA accumulates without the co-substrate (oxaloacetate) of citrate synthase.
The Malate anaplerotic pathway control state (M alone) is not an ET-pathway competent substrate state in many mt-preparations, since oxaloacetate accumulates without the co-substrate (acetyl-CoA) of citrate synthase.