ID   COX3_ENTDO              Reviewed;         204 AA.
AC   Q35242;
DT   15-JUL-1998, integrated into UniProtKB/Swiss-Prot.
DT   01-NOV-1996, sequence version 1.
DT   25-MAY-2022, entry version 90.
DE   RecName: Full=Cytochrome c oxidase subunit 3;
DE            EC=7.1.1.9;
DE   AltName: Full=Cytochrome c oxidase polypeptide III;
DE   Flags: Fragment;
GN   Name=COIII;
OS   Enteroctopus dofleini (North Pacific giant octopus) (Octopus dofleini).
OG   Mitochondrion.
OC   Eukaryota; Metazoa; Spiralia; Lophotrochozoa; Mollusca; Cephalopoda;
OC   Coleoidea; Octopodiformes; Octopoda; Incirrata; Octopodidae; Enteroctopus.
OX   NCBI_TaxID=267067;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [GENOMIC DNA].
RX   PubMed=7663761; DOI=10.1006/mpev.1995.1016;
RA   Barriga Sosa I.A., Beckenbach K., Hartwick B., Smith M.J.;
RT   "The molecular phylogeny of five eastern north Pacific octopus species.";
RL   Mol. Phylogenet. Evol. 4:163-174(1995).
CC   -!- FUNCTION: Component of the cytochrome c oxidase, the last enzyme in the
CC       mitochondrial electron transport chain which drives oxidative
CC       phosphorylation. The respiratory chain contains 3 multisubunit
CC       complexes succinate dehydrogenase (complex II, CII), ubiquinol-
CC       cytochrome c oxidoreductase (cytochrome b-c1 complex, complex III,
CC       CIII) and cytochrome c oxidase (complex IV, CIV), that cooperate to
CC       transfer electrons derived from NADH and succinate to molecular oxygen,
CC       creating an electrochemical gradient over the inner membrane that
CC       drives transmembrane transport and the ATP synthase. Cytochrome c
CC       oxidase is the component of the respiratory chain that catalyzes the
CC       reduction of oxygen to water. Electrons originating from reduced
CC       cytochrome c in the intermembrane space (IMS) are transferred via the
CC       dinuclear copper A center (CU(A)) of subunit 2 and heme A of subunit 1
CC       to the active site in subunit 1, a binuclear center (BNC) formed by
CC       heme A3 and copper B (CU(B)). The BNC reduces molecular oxygen to 2
CC       water molecules using 4 electrons from cytochrome c in the IMS and 4
CC       protons from the mitochondrial matrix. {ECO:0000250|UniProtKB:P00420}.
CC   -!- CATALYTIC ACTIVITY:
CC       Reaction=4 Fe(II)-[cytochrome c] + 8 H(+)(in) + O2 = 4 Fe(III)-
CC         [cytochrome c] + 4 H(+)(out) + 2 H2O; Xref=Rhea:RHEA:11436,
CC         Rhea:RHEA-COMP:10350, Rhea:RHEA-COMP:14399, ChEBI:CHEBI:15377,
CC         ChEBI:CHEBI:15378, ChEBI:CHEBI:15379, ChEBI:CHEBI:29033,
CC         ChEBI:CHEBI:29034; EC=7.1.1.9;
CC         Evidence={ECO:0000250|UniProtKB:P00420};
CC       PhysiologicalDirection=left-to-right; Xref=Rhea:RHEA:11437;
CC         Evidence={ECO:0000250|UniProtKB:P00420};
CC   -!- SUBUNIT: Component of the cytochrome c oxidase (complex IV, CIV), a
CC       multisubunit enzyme composed of a catalytic core of 3 subunits and
CC       several supernumerary subunits. The complex exists as a monomer or a
CC       dimer and forms supercomplexes (SCs) in the inner mitochondrial
CC       membrane with ubiquinol-cytochrome c oxidoreductase (cytochrome b-c1
CC       complex, complex III, CIII). {ECO:0000250|UniProtKB:P00420}.
CC   -!- SUBCELLULAR LOCATION: Mitochondrion inner membrane
CC       {ECO:0000250|UniProtKB:P00420}; Multi-pass membrane protein
CC       {ECO:0000250|UniProtKB:P00420}.
CC   -!- SIMILARITY: Belongs to the cytochrome c oxidase subunit 3 family.
CC       {ECO:0000305}.
CC   ---------------------------------------------------------------------------
CC   Copyrighted by the UniProt Consortium, see https://www.uniprot.org/terms
CC   Distributed under the Creative Commons Attribution (CC BY 4.0) License
CC   ---------------------------------------------------------------------------
DR   EMBL; X83103; CAA58165.1; -; Genomic_DNA.
DR   AlphaFoldDB; Q35242; -.
DR   SMR; Q35242; -.
DR   GO; GO:0016021; C:integral component of membrane; IEA:UniProtKB-KW.
DR   GO; GO:0005743; C:mitochondrial inner membrane; IEA:UniProtKB-SubCell.
DR   GO; GO:0004129; F:cytochrome-c oxidase activity; IEA:UniProtKB-EC.
DR   GO; GO:0019646; P:aerobic electron transport chain; IEA:InterPro.
DR   CDD; cd01665; Cyt_c_Oxidase_III; 1.
DR   Gene3D; 1.20.120.80; -; 1.
DR   InterPro; IPR024791; Cyt_c/ubiquinol_Oxase_su3.
DR   InterPro; IPR033945; Cyt_c_oxase_su3_dom.
DR   InterPro; IPR000298; Cyt_c_oxidase-like_su3.
DR   InterPro; IPR035973; Cyt_c_oxidase_su3-like_sf.
DR   InterPro; IPR013833; Cyt_c_oxidase_su3_a-hlx.
DR   PANTHER; PTHR11403; PTHR11403; 1.
DR   Pfam; PF00510; COX3; 1.
DR   SUPFAM; SSF81452; SSF81452; 1.
DR   PROSITE; PS50253; COX3; 1.
PE   3: Inferred from homology;
KW   Membrane; Mitochondrion; Mitochondrion inner membrane; Translocase;
KW   Transmembrane; Transmembrane helix.
FT   CHAIN           <1..>204
FT                   /note="Cytochrome c oxidase subunit 3"
FT                   /id="PRO_0000183814"
FT   TRANSMEM        12..32
FT                   /note="Helical"
FT                   /evidence="ECO:0000255"
FT   TRANSMEM        56..76
FT                   /note="Helical"
FT                   /evidence="ECO:0000255"
FT   TRANSMEM        101..121
FT                   /note="Helical"
FT                   /evidence="ECO:0000255"
FT   TRANSMEM        133..153
FT                   /note="Helical"
FT                   /evidence="ECO:0000255"
FT   TRANSMEM        171..191
FT                   /note="Helical"
FT                   /evidence="ECO:0000255"
FT   NON_TER         1
FT   NON_TER         204
SQ   SEQUENCE   204 AA;  23425 MW;  7B3451AFC57048C6 CRC64;
     LTTGLSSWFH NYGNLLLMLG FLLMIMTMIQ WWRDIIREST FQGFHTTKVY NGLRWGMMLF
     IVSEICFFFA FFWAYFHSSL APNTDIGACW PPINIYPLNP FQIPLLNTAI LLSSGVSVTW
     AHHSLMSNKL NPAIHSMTIT ITLGFYFTFL QMMEYIEASF SISDSIYGST FFVATGFHGL
     HVIIGSTFLF MCLIRIIMNH FSST