ID   CYB_CROVV               Reviewed;         128 AA.
AC   Q95776;
DT   15-JUL-1998, integrated into UniProtKB/Swiss-Prot.
DT   01-FEB-1997, sequence version 1.
DT   03-AUG-2022, entry version 80.
DE   RecName: Full=Cytochrome b;
DE   AltName: Full=Complex III subunit 3;
DE   AltName: Full=Complex III subunit III;
DE   AltName: Full=Cytochrome b-c1 complex subunit 3;
DE   AltName: Full=Ubiquinol-cytochrome-c reductase complex cytochrome b subunit;
DE   Flags: Fragment;
GN   Name=MT-CYB; Synonyms=COB, CYTB, MTCYB;
OS   Crotalus viridis viridis (Prairie rattlesnake).
OG   Mitochondrion.
OC   Eukaryota; Metazoa; Chordata; Craniata; Vertebrata; Euteleostomi;
OC   Lepidosauria; Squamata; Bifurcata; Unidentata; Episquamata; Toxicofera;
OC   Serpentes; Colubroidea; Viperidae; Crotalinae; Crotalus.
OX   NCBI_TaxID=8742;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [GENOMIC DNA].
RA   Cullings K.W., Morafka D.J., Hernandez J., Roberts J.W.;
RL   Submitted (JUL-1996) to the EMBL/GenBank/DDBJ databases.
CC   -!- FUNCTION: Component of the ubiquinol-cytochrome c reductase complex
CC       (complex III or cytochrome b-c1 complex) that is part of the
CC       mitochondrial respiratory chain. The b-c1 complex mediates electron
CC       transfer from ubiquinol to cytochrome c. Contributes to the generation
CC       of a proton gradient across the mitochondrial membrane that is then
CC       used for ATP synthesis. {ECO:0000250|UniProtKB:P00157}.
CC   -!- COFACTOR:
CC       Name=heme b; Xref=ChEBI:CHEBI:60344;
CC         Evidence={ECO:0000250|UniProtKB:P00157};
CC       Note=Binds 2 heme b groups non-covalently.
CC       {ECO:0000250|UniProtKB:P00157};
CC   -!- SUBUNIT: The cytochrome bc1 complex contains 3 respiratory subunits
CC       (MT-CYB, CYC1 and UQCRFS1), 2 core proteins (UQCRC1 and UQCRC2) and
CC       probably 6 low-molecular weight proteins.
CC       {ECO:0000250|UniProtKB:P00157}.
CC   -!- SUBCELLULAR LOCATION: Mitochondrion inner membrane
CC       {ECO:0000250|UniProtKB:P00157}; Multi-pass membrane protein
CC       {ECO:0000250|UniProtKB:P00157}.
CC   -!- MISCELLANEOUS: Heme 1 (or BL or b562) is low-potential and absorbs at
CC       about 562 nm, and heme 2 (or BH or b566) is high-potential and absorbs
CC       at about 566 nm. {ECO:0000250}.
CC   -!- SIMILARITY: Belongs to the cytochrome b family. {ECO:0000255|PROSITE-
CC       ProRule:PRU00968}.
CC   -!- CAUTION: The full-length protein contains only eight transmembrane
CC       helices, not nine as predicted by bioinformatics tools.
CC       {ECO:0000250|UniProtKB:P00157}.
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; U65377; AAB06740.1; -; Genomic_DNA.
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:0070469; C:respirasome; IEA:UniProtKB-KW.
DR   GO; GO:0009055; F:electron transfer activity; IEA:InterPro.
DR   GO; GO:0046872; F:metal ion binding; IEA:UniProtKB-KW.
DR   GO; GO:0022904; P:respiratory electron transport chain; IEA:InterPro.
DR   Gene3D; 1.20.810.10; -; 1.
DR   InterPro; IPR005797; Cyt_b/b6_N.
DR   InterPro; IPR027387; Cytb/b6-like_sf.
DR   InterPro; IPR016174; Di-haem_cyt_TM.
DR   Pfam; PF00033; Cytochrome_B; 1.
DR   SUPFAM; SSF81342; SSF81342; 1.
DR   PROSITE; PS51002; CYTB_NTER; 1.
PE   3: Inferred from homology;
KW   Electron transport; Heme; Iron; Membrane; Metal-binding; Mitochondrion;
KW   Mitochondrion inner membrane; Respiratory chain; Transmembrane;
KW   Transmembrane helix; Transport; Ubiquinone.
FT   CHAIN           <1..>128
FT                   /note="Cytochrome b"
FT                   /id="PRO_0000060833"
FT   TRANSMEM        25..45
FT                   /note="Helical"
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00968"
FT   TRANSMEM        69..90
FT                   /note="Helical"
FT                   /evidence="ECO:0000250|UniProtKB:P00157"
FT   TRANSMEM        105..125
FT                   /note="Helical"
FT                   /evidence="ECO:0000250|UniProtKB:P00157"
FT   BINDING         75
FT                   /ligand="heme b"
FT                   /ligand_id="ChEBI:CHEBI:60344"
FT                   /ligand_label="b562"
FT                   /ligand_part="Fe"
FT                   /ligand_part_id="ChEBI:CHEBI:18248"
FT                   /note="axial binding residue"
FT                   /evidence="ECO:0000250|UniProtKB:P00157"
FT   BINDING         89
FT                   /ligand="heme b"
FT                   /ligand_id="ChEBI:CHEBI:60344"
FT                   /ligand_label="b566"
FT                   /ligand_part="Fe"
FT                   /ligand_part_id="ChEBI:CHEBI:18248"
FT                   /note="axial binding residue"
FT                   /evidence="ECO:0000250|UniProtKB:P00157"
FT   BINDING         126
FT                   /ligand="a ubiquinone"
FT                   /ligand_id="ChEBI:CHEBI:16389"
FT                   /evidence="ECO:0000250|UniProtKB:P00157"
FT   NON_TER         1
FT   NON_TER         128
SQ   SEQUENCE   128 AA;  14607 MW;  993267807EB97550 CRC64;
     MTHQHLLTMF NLLPVGXNIS TWWNFGSMLL SCLTIQIITG FFLAIHYTAN INMAFSSIMH
     ISRDVPYGWI MQNTHAIGXS LFFICIYIHI ARGIYYGSYL NKEVWLSGTT LLITLMATAS
     XXMCYHDT