ID   COX3_PISOC              Reviewed;         260 AA.
AC   P25003;
DT   01-MAR-1992, integrated into UniProtKB/Swiss-Prot.
DT   01-MAR-1992, sequence version 1.
DT   22-FEB-2023, entry version 102.
DE   RecName: Full=Cytochrome c oxidase subunit 3;
DE            EC=7.1.1.9;
DE   AltName: Full=Cytochrome c oxidase polypeptide III;
GN   Name=COIII;
OS   Pisaster ochraceus (Ochre sea star) (Asterias ochracea).
OG   Mitochondrion.
OC   Eukaryota; Metazoa; Echinodermata; Eleutherozoa; Asterozoa; Asteroidea;
OC   Forcipulatacea; Forcipulatida; Asteriidae; Pisaster.
OX   NCBI_TaxID=7612;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [GENOMIC DNA].
RX   PubMed=1976816; DOI=10.1007/bf02109496;
RA   Smith M.J., Banfield D.K., Doteval K., Gorski S., Kowbel D.J.;
RT   "Nucleotide sequence of nine protein-coding genes and 22 tRNAs in the
RT   mitochondrial DNA of the sea star Pisaster ochraceus.";
RL   J. Mol. Evol. 31:195-204(1990).
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}.
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DR   EMBL; X55514; CAA39129.1; -; Genomic_DNA.
DR   PIR; S14210; S14210.
DR   AlphaFoldDB; P25003; -.
DR   SMR; P25003; -.
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; 1.10.287.70; -; 1.
DR   Gene3D; 1.20.120.80; Cytochrome c oxidase, subunit III, four-helix bundle; 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:SF7; CYTOCHROME C OXIDASE SUBUNIT 3; 1.
DR   PANTHER; PTHR11403; CYTOCHROME C OXIDASE SUBUNIT III; 1.
DR   Pfam; PF00510; COX3; 1.
DR   SUPFAM; SSF81452; Cytochrome c oxidase subunit III-like; 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..260
FT                   /note="Cytochrome c oxidase subunit 3"
FT                   /id="PRO_0000183833"
FT   TRANSMEM        30..50
FT                   /note="Helical"
FT                   /evidence="ECO:0000255"
FT   TRANSMEM        81..101
FT                   /note="Helical"
FT                   /evidence="ECO:0000255"
FT   TRANSMEM        126..146
FT                   /note="Helical"
FT                   /evidence="ECO:0000255"
FT   TRANSMEM        158..178
FT                   /note="Helical"
FT                   /evidence="ECO:0000255"
FT   TRANSMEM        196..216
FT                   /note="Helical"
FT                   /evidence="ECO:0000255"
FT   TRANSMEM        239..259
FT                   /note="Helical"
FT                   /evidence="ECO:0000255"
SQ   SEQUENCE   260 AA;  29648 MW;  2A3BD9B47188841E CRC64;
     MTHQHPYHLV DQSPWPLTGA ISALMMTSGL ILWFHINSTI LFILGTVLLV LTIINWWRDI
     IREATFQGFH TLSVSNGLRY GMILFITSEV CLFFAFFWAF FHSSLAPTIE LGVSWPPTGI
     TPINPFLVPL LNTAVLLSSG VTVTWAHHSI LSGNRVEAIQ SLTLTVFLGV YFTILQAWEY
     FDSPFTIADS VYGSTFFVAT GFHGLHVLIG TAFLAVCLLR LYNFHFSNHH HFGFEAASWY
     WHFVDVVWLF LYICIYWWGS
//