Component of the ubiquinol-cytochrome c oxidoreductase, a multisubunit
transmembrane complex that is part of the mitochondrial electron transport chain which
drives oxidative phosphorylation. The respiratory chain contains 3 multisubunit
complexes succinate dehydrogenase (complex II, CII, ubiquinol-cytochrome c
oxidoreductase (cytochrome b-c1 complex, complex III, CIII and cytochrome c oxidase
(complex IV, CIV, that cooperate to transfer electrons derived from NADH and succinate
to molecular oxygen, creating an electrochemical gradient over the inner membrane
that drives transmembrane transport and the ATP synthase. The cytochrome b-c1
complex catalyzes electron transfer from ubiquinol to cytochrome c, linking this redox
reaction to translocation of protons across the mitochondrial inner membrane, with
protons being carried across the membrane as hydrogens on the quinol. In the process
called Q cycle, 2 protons are consumed from the matrix, 4 protons are released into the
intermembrane space and 2 electrons are passed to cytochrome c (By similarity. The 2
core subunits UQCRC1/QCR1 and UQCRC2/QCR2 are homologous to the 2 mitochondrialprocessing
peptidase (MPP subunits beta-MPP and alpha-MPP respectively, and they
seem to have preserved their MPP processing properties (By similarity. May be involved
in the in situ processing of UQCRFS1 into the mature Rieske protein and its mitochondrial
targeting sequence (MTS/subunit 9 when incorporated into complex III