ID   COX3_STRPU              Reviewed;         260 AA.
AC   P15546;
DT   01-APR-1990, integrated into UniProtKB/Swiss-Prot.
DT   01-APR-1990, sequence version 1.
DT   24-JAN-2024, entry version 112.
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   Strongylocentrotus purpuratus (Purple sea urchin).
OG   Mitochondrion.
OC   Eukaryota; Metazoa; Echinodermata; Eleutherozoa; Echinozoa; Echinoidea;
OC   Euechinoidea; Echinacea; Camarodonta; Echinidea; Strongylocentrotidae;
OC   Strongylocentrotus.
OX   NCBI_TaxID=7668;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [GENOMIC DNA].
RX   PubMed=3172215; DOI=10.1016/0022-2836(88)90452-4;
RA   Jacobs H.T., Elliott D.J., Math V.B., Farquharson A.;
RT   "Nucleotide sequence and gene organization of sea urchin mitochondrial
RT   DNA.";
RL   J. Mol. Biol. 202:185-217(1988).
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; X12631; -; NOT_ANNOTATED_CDS; Genomic_DNA.
DR   PIR; S01506; S01506.
DR   AlphaFoldDB; P15546; -.
DR   SMR; P15546; -.
DR   STRING; 7668.P15546; -.
DR   InParanoid; P15546; -.
DR   Proteomes; UP000007110; Unassembled WGS sequence.
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:0006123; P:mitochondrial electron transport, cytochrome c to oxygen; IBA:GO_Central.
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; Reference proteome;
KW   Translocase; Transmembrane; Transmembrane helix.
FT   CHAIN           1..260
FT                   /note="Cytochrome c oxidase subunit 3"
FT                   /id="PRO_0000183858"
FT   TRANSMEM        41..61
FT                   /note="Helical"
FT                   /evidence="ECO:0000255"
FT   TRANSMEM        81..101
FT                   /note="Helical"
FT                   /evidence="ECO:0000255"
FT   TRANSMEM        133..153
FT                   /note="Helical"
FT                   /evidence="ECO:0000255"
FT   TRANSMEM        161..181
FT                   /note="Helical"
FT                   /evidence="ECO:0000255"
FT   TRANSMEM        196..216
FT                   /note="Helical"
FT                   /evidence="ECO:0000255"
FT   TRANSMEM        238..258
FT                   /note="Helical"
FT                   /evidence="ECO:0000255"
SQ   SEQUENCE   260 AA;  29489 MW;  7416670412F81A00 CRC64;
     MAIQHPYHLV DQSPWPLDGA FSGLMMTSGN VLWFHTQKTN LTLVGFLLLI TNMVNWWRDI
     IRKANFQGSH TAIVNKGMRY GMILFITSEV CFFFAFFWAF FHSSLAPSVE IGVAWPPSGI
     TPLNPFLVPL LNTGVLLSSG VTLSWSHHSI LAGNRTESIQ ALFLTVALGS YFTALQAWEY
     IDAPFTIADS VYGSTFFVAT GFHGLQVIIG TTFLMVCLFR TAGRHFSTHH HFGFEAAAWY
     WHFVDVVWFV LYWLIYWWGA
//