ID   COX3_HETBL              Reviewed;         259 AA.
AC   O47475;
DT   01-DEC-2000, integrated into UniProtKB/Swiss-Prot.
DT   01-JUN-1998, sequence version 1.
DT   22-FEB-2023, entry version 100.
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   Heterololigo bleekeri (Spear squid) (Loligo bleekeri).
OG   Mitochondrion.
OC   Eukaryota; Metazoa; Spiralia; Lophotrochozoa; Mollusca; Cephalopoda;
OC   Coleoidea; Decapodiformes; Myopsida; Loliginidae; Heterololigo.
OX   NCBI_TaxID=1423826;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [GENOMIC DNA].
RA   Tomita K., Ueda T., Watanabe K.;
RT   "Completing of squid (Loligo breekeri) mitochondrial genome sequencing.";
RL   Submitted (DEC-1997) to the EMBL/GenBank/DDBJ databases.
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; AB009838; BAA24058.1; -; Genomic_DNA.
DR   EMBL; AB029616; BAB03645.1; -; Genomic_DNA.
DR   RefSeq; NP_062833.1; NC_002507.1.
DR   AlphaFoldDB; O47475; -.
DR   SMR; O47475; -.
DR   GeneID; 809435; -.
DR   CTD; 4514; -.
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..259
FT                   /note="Cytochrome c oxidase subunit 3"
FT                   /id="PRO_0000183801"
FT   TRANSMEM        13..33
FT                   /note="Helical"
FT                   /evidence="ECO:0000255"
FT   TRANSMEM        36..56
FT                   /note="Helical"
FT                   /evidence="ECO:0000255"
FT   TRANSMEM        80..100
FT                   /note="Helical"
FT                   /evidence="ECO:0000255"
FT   TRANSMEM        125..145
FT                   /note="Helical"
FT                   /evidence="ECO:0000255"
FT   TRANSMEM        154..174
FT                   /note="Helical"
FT                   /evidence="ECO:0000255"
FT   TRANSMEM        195..215
FT                   /note="Helical"
FT                   /evidence="ECO:0000255"
FT   TRANSMEM        237..257
FT                   /note="Helical"
FT                   /evidence="ECO:0000255"
SQ   SEQUENCE   259 AA;  29637 MW;  10B61CB81E5ACA41 CRC64;
     MIRNPFHLVE YSPWPLTGSL GAMFLTVGLT SWFHNHGFIT MLLGLFLVLM TMFQWWRDII
     RESTFQGYHT MKVSLGMRMG MVLFITSEIC FFFAFFWAYF HSSLAPNTDI GASWPPLHIN
     PLNPFQIPLL NTAILLASGV TVTWAHHSLM GGNHAEATQS MVLTVILGGY FTLLQAEEYM
     EAPFSIADSV YGATFFVATG FHGLHVIIGS VFLLICLFRM LIHHFSTNHH FGFEAAAWYW
     HFVDVVWLIL YTCIYWWGS
//