F-junction: Difference between revisions
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|description=[[File:SUIT-catg F.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 | | The '''F-junction''' is a junction for [[convergent electron flow]] in the [[electron transfer system]] (ETS) from fatty acids ([[ETS substrate types |F-junction 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 (the [[FAO]] substrate 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 2014 MitoPathways]] | ||
}} | }} |
Revision as of 07:37, 10 September 2016
Description
The F-junction is a junction for convergent electron flow in the electron transfer system (ETS) from fatty acids (F-junction 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 (the FAO substrate 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 2014 MitoPathways
MitoPedia concepts:
MiP concept,
SUIT concept
MitoPedia methods:
Respirometry
Contributed by Gnaiger E 2016-02-12