Phosphorylation pathway: Difference between revisions
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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 | 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 '''Pยป-system'''. The Pยป-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 Pยป-system, controlling local AMP and ADP concentrations and forming [[metabolic channel]]s. Since substrate-level phosphorylation is involved in the TCA-cycle, the Pยป-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 | ||
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ย Communicated by [[Gnaiger E]] 2010-08-15 | ย 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 [[electron transfer-pathway state]], may be limited by the capacity of the phosphorylation system. Mitochondria are the location of the chemiosmotic Pยป-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 Pยป). This step must be considered in the Pยป-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. | :::: [[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 Pยป-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 Pยป). This step must be considered in the Pยป-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 11:27, 2 June 2020
Description
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 Pยป-system. The Pยป-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 Pยป-system, controlling local AMP and ADP concentrations and forming metabolic channels. Since substrate-level phosphorylation is involved in the TCA-cycle, the Pยป-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 Pยป-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 Pยป). This step must be considered in the Pยป-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.