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Difference between revisions of "F-junction"

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{{MitoPedia
{{MitoPedia
|description=[[File:SUIT-Catg NF.jpg|right|300px|F-junction]]
|description=[[File:SUIT-catg F.jpg|right|300px|F-junction]]
The '''F-junction''' is a junction for [[convergent electron flow]] in the [[electron transfer system]] (ETS) from fatty acids ([[ETS substrate types |type F substrates]]) through [[fatty acyl CoA dehydrogenase]] (reduced form [[FADH2]]) to [[electron transferring flavoprotein]] (CETF), and further transfer through the [[Q-junction]] to [[Complex III]] (CIII). The concept of the F-junction and [[N-junction]] provides a basis for defining [[categories of SUIT protocols]]. Fatty acid oxidation (FAO) not only depends on electron transfer through the F-junction (which is typically rate-limiting) but simultaneously generates NADH and thus depends on N-junction throughput. Hence FAO can be inhibited completely by inhibition of Complex I (CI). In addition and independent of this source of NADH, the type N substrate malate is required as a co-substrate for FAO in mt-preparations, since accumulation of AcetylCo inhibits FAO in the absence of malate. Malate is oxidized in a reaction catalyzed by malate dehydrogenase to oxaloacetate (yielding NADH), which then stimulates the entry of AcetylCo into the TCA cycle catalyzed by citrate synthase.
The '''F-junction''' is a junction for [[convergent electron flow]] in the [[electron transfer pathway]] (ET-pathway) from fatty acids through [[fatty acyl CoA dehydrogenase]] (reduced form [[FADH2]]) to [[electron transferring flavoprotein]] (CETF), and further transfer through the [[Q-junction]] to [[Complex III]] (CIII). The concept of the F-junction and [[N-junction]] provides a basis for defining [[categories of SUIT protocols]]. Fatty acid oxidation, in the [[F-pathway control state]], not only depends on electron transfer through the F-junction (which is typically rate-limiting) but simultaneously generates NADH and thus depends on N-junction throughput. Hence FAO can be inhibited completely by inhibition of Complex I (CI). In addition and independent of this source of NADH, the N-junction substrate malate is required as a co-substrate for FAO in mt-preparations, since accumulation of AcetylCoA inhibits FAO in the absence of malate. Malate is oxidized in a reaction catalyzed by malate dehydrogenase to oxaloacetate (yielding NADH), which then stimulates the entry of AcetylCoA into the TCA cycle catalyzed by citrate synthase.
|info=[[Gnaiger 2014 MitoPathways]]
|info=[[Gnaiger 2020 BEC MitoPathways]]
}}
Communicated by [[Gnaiger E]] 2016-02-12, edited 2016-11-08.
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{{MitoPedia concepts
|mitopedia concept=MiP concept, SUIT concept
}}
}}
{{MitoPedia methods
{{MitoPedia methods
|mitopedia method=Respirometry
|mitopedia method=Respirometry
}}
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{{MitoPedia O2k and high-resolution respirometry
{{Labeling
|mitopedia O2k and high-resolution respirometry=SUIT protocol
|additional=MitoPedia:FAT4BRAIN
}}
}}
Contributed by [[Gnaiger E]] 2016-02-12

Latest revision as of 16:06, 18 January 2022


high-resolution terminology - matching measurements at high-resolution


F-junction

Description

F-junction

The F-junction is a junction for convergent electron flow in the electron transfer pathway (ET-pathway) from fatty acids through fatty acyl CoA dehydrogenase (reduced form FADH2) to electron transferring flavoprotein (CETF), and further transfer through the Q-junction to Complex III (CIII). The concept of the F-junction and N-junction provides a basis for defining categories of SUIT protocols. Fatty acid oxidation, in the F-pathway control state, not only depends on electron transfer through the F-junction (which is typically rate-limiting) but simultaneously generates NADH and thus depends on N-junction throughput. Hence FAO can be inhibited completely by inhibition of Complex I (CI). In addition and independent of this source of NADH, the N-junction substrate malate is required as a co-substrate for FAO in mt-preparations, since accumulation of AcetylCoA inhibits FAO in the absence of malate. Malate is oxidized in a reaction catalyzed by malate dehydrogenase to oxaloacetate (yielding NADH), which then stimulates the entry of AcetylCoA into the TCA cycle catalyzed by citrate synthase.


Reference: Gnaiger 2020 BEC MitoPathways

Communicated by Gnaiger E 2016-02-12, edited 2016-11-08.


MitoPedia concepts: MiP concept, SUIT concept 


MitoPedia methods: Respirometry 


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MitoPedia:FAT4BRAIN