ID   QCR2_EUGGR              Reviewed;         474 AA.
AC   P43265;
DT   01-NOV-1995, integrated into UniProtKB/Swiss-Prot.
DT   01-NOV-1995, sequence version 1.
DT   25-MAY-2022, entry version 88.
DE   RecName: Full=Ubiquinol-cytochrome-c reductase complex core protein 2, mitochondrial;
DE   Flags: Precursor;
OS   Euglena gracilis.
OC   Eukaryota; Discoba; Euglenozoa; Euglenida; Spirocuta; Euglenophyceae;
OC   Euglenales; Euglenaceae; Euglena.
OX   NCBI_TaxID=3039;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [MRNA], AND PROTEIN SEQUENCE OF 43-54.
RC   STRAIN=SM-ZK;
RX   PubMed=8188644; DOI=10.1093/oxfordjournals.jbchem.a124312;
RA   Cui J.-Y., Mukai K., Saeki K., Matsubara H.;
RT   "Molecular cloning and nucleotide sequences of cDNAs encoding subunits I,
RT   II, and IX of Euglena gracilis mitochondrial complex III.";
RL   J. Biochem. 115:98-107(1994).
CC   -!- FUNCTION: Component of the ubiquinol-cytochrome c oxidoreductase, a
CC       multisubunit transmembrane complex that is part of the mitochondrial
CC       electron transport chain which drives oxidative phosphorylation. The
CC       respiratory chain contains 3 multisubunit complexes succinate
CC       dehydrogenase (complex II, CII), ubiquinol-cytochrome c oxidoreductase
CC       (cytochrome b-c1 complex, complex III, CIII) and cytochrome c oxidase
CC       (complex IV, CIV), that cooperate to transfer electrons derived from
CC       NADH and succinate to molecular oxygen, creating an electrochemical
CC       gradient over the inner membrane that drives transmembrane transport
CC       and the ATP synthase. The cytochrome b-c1 complex catalyzes electron
CC       transfer from ubiquinol to cytochrome c, linking this redox reaction to
CC       translocation of protons across the mitochondrial inner membrane, with
CC       protons being carried across the membrane as hydrogens on the quinol.
CC       In the process called Q cycle, 2 protons are consumed from the matrix,
CC       4 protons are released into the intermembrane space and 2 electrons are
CC       passed to cytochrome c. {ECO:0000250|UniProtKB:P07257}.
CC   -!- SUBUNIT: Component of the ubiquinol-cytochrome c oxidoreductase
CC       (cytochrome b-c1 complex, complex III, CIII), a multisubunit enzyme
CC       composed of 3 respiratory subunits cytochrome b, cytochrome c1 and
CC       Rieske protein, 2 core protein subunits, and additional low-molecular
CC       weight protein subunits. The complex exists as an obligatory dimer and
CC       forms supercomplexes (SCs) in the inner mitochondrial membrane with
CC       cytochrome c oxidase (complex IV, CIV). {ECO:0000250|UniProtKB:P07257}.
CC   -!- SUBCELLULAR LOCATION: Mitochondrion inner membrane
CC       {ECO:0000250|UniProtKB:P07257}; Peripheral membrane protein
CC       {ECO:0000250|UniProtKB:P07257}; Matrix side
CC       {ECO:0000250|UniProtKB:P07257}.
CC   -!- SIMILARITY: Belongs to the peptidase M16 family. UQCRC2/QCR2 subfamily.
CC       {ECO:0000305}.
CC   -!- CAUTION: Does not seem to have a protease activity as it lack the zinc-
CC       binding site. {ECO:0000305}.
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DR   EMBL; D16672; BAA04080.1; -; mRNA.
DR   PIR; JX0301; JX0301.
DR   AlphaFoldDB; P43265; -.
DR   SMR; P43265; -.
DR   GO; GO:0005743; C:mitochondrial inner membrane; IEA:UniProtKB-SubCell.
DR   GO; GO:0070469; C:respirasome; IEA:UniProtKB-KW.
DR   GO; GO:0046872; F:metal ion binding; IEA:InterPro.
DR   InterPro; IPR011249; Metalloenz_LuxS/M16.
DR   InterPro; IPR011765; Pept_M16_N.
DR   Pfam; PF00675; Peptidase_M16; 1.
DR   SUPFAM; SSF63411; SSF63411; 2.
PE   1: Evidence at protein level;
KW   Direct protein sequencing; Electron transport; Membrane; Mitochondrion;
KW   Mitochondrion inner membrane; Respiratory chain; Transit peptide;
KW   Transport.
FT   TRANSIT         1..42
FT                   /note="Mitochondrion"
FT                   /evidence="ECO:0000269|PubMed:8188644"
FT   CHAIN           43..474
FT                   /note="Ubiquinol-cytochrome-c reductase complex core
FT                   protein 2, mitochondrial"
FT                   /id="PRO_0000026802"
SQ   SEQUENCE   474 AA;  51074 MW;  4CDF5C27AF119175 CRC64;
     MKSVVRSKGT QALFRRFSSA LGDSINPNQV GVGDNVIRVN GRLFEVDKVQ EKGLKTSVLD
     NGTKVITLDN GGSVAQLTFL YKDGPVYENI FNAGISSFMK HALTKDGLTS SEYITKTFLQ
     KAGIIVHEPT VVNKSAIAFT VEGFRDTLAQ PAVADKFWQS LLFPRFSPEN VKEVKRLVEL
     ESKETKRDSP FAYLQDILHK TAFKGSPLGH TSFVPAYNLG YIDSNKLFDR WDAHYGFGNI
     AVIATNIEHE AVLAAITDSA WVARAHNKVG GVAAPASKYS GGEGYDVVHR AKEFDDQFTD
     VYSTYTAYAF KAPGRSNLKE HAASLVIAQA LSNAVSPVLN TSFAPKRLEV FYQAYDTVGL
     IGLSSVQASN AQLKAFKAAL SKIGTLSEAD LAVHKSAALL TAYGNVESWR ATQATLIDSF
     NTTGQPLSPL EIVSAIKAVS ADTVKSVVAT MLGSPATLVH HGDSPCAPTL DALQ