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Difference between revisions of "Phosphorylation pathway"

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|abbr=DT
|abbr=DT
|description=[[File:Phosphorylation system.jpg|thumb|left|250px|From Gnaiger 2014 MitoPathways]]
|description=[[File:Phosphorylation system.jpg|thumb|left|250px|From Gnaiger 2014 MitoPathways]]
The '''phosphorylation system''' is the functional unit utilizing the protonmotive force to phosphorylate ADP (D) to ATP (T), and may be defined more specifically as the DT-phosphorylation system or '''DT-system'''. The DT-system consists of [[adenine nucleotide translocase]], [[phosphate carrier]], and [[ATP synthase]]. Mitochondrial [[adenylate kinase]], mt-[[creatine kinase]] and mt-[[hexokinase]] constitute extended components of the DT-phosphorylation system, controlling local AMP and ADP concentrations and forming [[metabolic channel]]s. Since substrate-level phosphorylation is involved in the TCA-cycle, the mtDT system includes succinyl-CoA synthase (GDP to GTP or ADP to ATP).
The '''phosphorylation pathway''' (phosphorylation system) is the functional unit utilizing the protonmotive force to phosphorylate ADP (D) to ATP (T), and may be defined more specifically as the '''-system'''. The -system consists of [[adenine nucleotide translocase]], [[phosphate carrier]], and [[ATP synthase]]. Mitochondrial [[adenylate kinase]], mt-[[creatine kinase]] and mt-[[hexokinase]] constitute extended components of the -system, controlling local AMP and ADP concentrations and forming [[metabolic channel]]s. Since substrate-level phosphorylation is involved in the TCA-cycle, the P»-system includes [[succinyl-CoA ligase]] (GDP to GTP or ADP to ATP).
|info=[[Gnaiger 2009 Int J Biochem Cell Biol]]
|info=[[Gnaiger 2009 Int J Biochem Cell Biol]]
}}
}}
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|mitopedia topic=Enzyme
|mitopedia topic=Enzyme
}}
}}
  Communicated by [[Gnaiger E]] 2010-08-15, edited 2016-08-26.
  Communicated by [[Gnaiger E]] (2010-08-15) last update 2020-06-02.


== OXPHOS and substrate level phosphorylation ==
== OXPHOS and substrate-level phosphorylation ==


:::: [[OXPHOS capacity]], measured as oxygen flux in coupled, ADP- and Pi-saturated mitochondria in an [[Pathway control state|ETS-competent substrate state]], may be limited by the phosphorylation system capacity. Mitochondria are the location of the chemiosmotic DT-system, but additionally carry out substrate-level phosphorylation in the TCA-cycle at the step of [[succinyl-CoA synthase]], phosphorylating GDP to GTP or ADP to ATP (taken together as DT). This step must be considered in the mtDT-phosphorylation system. If succinate is externally added to mt-preparations, succinyl-CoA synthase is not involved. However, if succinate is formed in the mt-matrix from 2-oxoglutarate (alpha-ketoglutarate), substrate-level phosphorylation at succinyl-CoA synthase must be accounted for in the interpretation of P/O (P/O<sub>2</sub>) ratios.
:::: [[OXPHOS capacity]], measured as oxygen flux in coupled, ADP- and Pi-saturated mitochondria in an [[electron-transfer-pathway state]], may be limited by the capacity of the phosphorylation system. Mitochondria are the location of the chemiosmotic -system, but additionally carry out substrate-level phosphorylation in the TCA-cycle at the step of [[succinyl-CoA ligase]], phosphorylating GDP to GTP or ADP to ATP (taken together as ). This step must be considered in the -system. If succinate is externally added to mt-preparations, succinyl-CoA ligase is not involved. However, if succinate is formed in the mt-matrix from 2-oxoglutarate (alpha-ketoglutarate), substrate-level phosphorylation at succinyl-CoA ligase must be accounted for in the interpretation of P/O<sub>2</sub> ratios.

Latest revision as of 10:27, 2 June 2020


high-resolution terminology - matching measurements at high-resolution


Phosphorylation pathway

Description

From Gnaiger 2014 MitoPathways

The phosphorylation pathway (phosphorylation system) is the functional unit utilizing the protonmotive force to phosphorylate ADP (D) to ATP (T), and may be defined more specifically as the P»-system. The P»-system consists of adenine nucleotide translocase, phosphate carrier, and ATP synthase. Mitochondrial adenylate kinase, mt-creatine kinase and mt-hexokinase constitute extended components of the P»-system, controlling local AMP and ADP concentrations and forming metabolic channels. Since substrate-level phosphorylation is involved in the TCA-cycle, the P»-system includes succinyl-CoA ligase (GDP to GTP or ADP to ATP).

Abbreviation: DT

Reference: Gnaiger 2009 Int J Biochem Cell Biol


MitoPedia concepts: MiP concept, SUIT concept 


MitoPedia topics: Enzyme 

Communicated by Gnaiger E (2010-08-15) last update 2020-06-02.

OXPHOS and substrate-level phosphorylation

OXPHOS capacity, measured as oxygen flux in coupled, ADP- and Pi-saturated mitochondria in an electron-transfer-pathway state, may be limited by the capacity of the phosphorylation system. Mitochondria are the location of the chemiosmotic P»-system, but additionally carry out substrate-level phosphorylation in the TCA-cycle at the step of succinyl-CoA ligase, phosphorylating GDP to GTP or ADP to ATP (taken together as P»). This step must be considered in the P»-system. If succinate is externally added to mt-preparations, succinyl-CoA ligase is not involved. However, if succinate is formed in the mt-matrix from 2-oxoglutarate (alpha-ketoglutarate), substrate-level phosphorylation at succinyl-CoA ligase must be accounted for in the interpretation of P/O2 ratios.