ID   COX3_METSE              Reviewed;         262 AA.
AC   O47491;
DT   15-DEC-1998, integrated into UniProtKB/Swiss-Prot.
DT   01-JUN-1998, sequence version 1.
DT   25-MAY-2022, entry version 93.
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   Metridium senile (Brown sea anemone) (Frilled sea anemone).
OG   Mitochondrion.
OC   Eukaryota; Metazoa; Cnidaria; Anthozoa; Hexacorallia; Actiniaria;
OC   Nynantheae; Metridiidae; Metridium.
OX   NCBI_TaxID=6116;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [GENOMIC DNA].
RC   STRAIN=White morph;
RA   Beagley C.T., Okimoto R., Wolstenholme D.R.;
RL   Submitted (APR-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; AF000023; AAC04629.1; -; Genomic_DNA.
DR   PIR; T11883; T11883.
DR   RefSeq; NP_009252.1; NC_000933.1.
DR   AlphaFoldDB; O47491; -.
DR   SMR; O47491; -.
DR   GeneID; 808768; -.
DR   CTD; 4514; -.
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..262
FT                   /note="Cytochrome c oxidase subunit 3"
FT                   /id="PRO_0000183808"
FT   TRANSMEM        16..36
FT                   /note="Helical"
FT                   /evidence="ECO:0000255"
FT   TRANSMEM        39..59
FT                   /note="Helical"
FT                   /evidence="ECO:0000255"
FT   TRANSMEM        83..103
FT                   /note="Helical"
FT                   /evidence="ECO:0000255"
FT   TRANSMEM        128..148
FT                   /note="Helical"
FT                   /evidence="ECO:0000255"
FT   TRANSMEM        160..180
FT                   /note="Helical"
FT                   /evidence="ECO:0000255"
FT   TRANSMEM        198..218
FT                   /note="Helical"
FT                   /evidence="ECO:0000255"
FT   TRANSMEM        241..261
FT                   /note="Helical"
FT                   /evidence="ECO:0000255"
SQ   SEQUENCE   262 AA;  29631 MW;  15EC3F1270D3C819 CRC64;
     MKSTVYHPYH LVDPSPWPYV GACGALFITV GSVVYFHYSQ TWVLLMGAIT LSLTMIVWWR
     DVIREATFQG LHTMVVKQGL KYGMLLFILS EVLFFFSFFW AFFHSSIAPN IELGAVWPPQ
     GINPLNPFSV PLLNTAVLLS SGATVTWAHH ALISGKKTEA INGLTITVVL GLIFTGLQAM
     EYYEAPFAIS DSVYGSTFFV ATGFHGMHVI IGTTFLAVCL ARLVYHQFTR HHHLGFEAAS
     WYWHFVDVVW LFLYICIYWW GS