Q-junction

high-resolution terminology - matching measurements at high-resolution

Q-junction

Description

The Q-junction is a junction for convergent electron flow in the Electron transfer pathway (ET-pathway) from type N substrates and mt-matrix dehydrogenases through Complex I (CI), from type F substrates and FA oxidation through electron-transferring flavoprotein Complex (CETF), from succinate (S) through Complex II (CII), from glycerophosphate (Gp) through glycerophosphate dehydrogenase Complex (CGpDH), from choline through choline dehydrogenase, from dihydro-orotate through dihydro-orotate dehydrogenase, and other enzyme Complexes into the Q-cycle (ubiquinol/ubiquinone), and further downstream to Complex III (CIII) and Complex IV (CIV). The concept of the Q-junction, with the N-junction and F-junction upstream, provides the rationale for defining Electron-transfer-pathway states and categories of SUIT protocols.

Reference: Gnaiger 2009 Int J Biochem Cell Biol, Gnaiger 2020 BEC MitoPathways

MitoPedia concepts: MiP concept, SUIT concept

MitoPedia methods: Respirometry

MitoPedia topics: Enzyme

Contributed by Gnaiger E 2010-08-15; edited 2016-02-12, 2016-03-28.

Convergent NS-linked electron flow at the Q-junction, exerting an additive effect on flux, versus electron gaiting for separation of single N- and S-input pathways (upper panel: Gnaiger 2009; lower panel: Hatefi 1962 J Biol Chem-XLII). Modified Figure in Gnaiger 2020 BEC MitoPathways.