ID A0A1P8D674_9FLOR Unreviewed; 215 AA. AC A0A1P8D674; DT 12-APR-2017, integrated into UniProtKB/TrEMBL. DT 12-APR-2017, sequence version 1. DT 24-JAN-2024, entry version 20. DE RecName: Full=Cytochrome b6 {ECO:0000256|ARBA:ARBA00035697, ECO:0000256|HAMAP-Rule:MF_00633}; GN Name=petB {ECO:0000256|HAMAP-Rule:MF_00633, GN ECO:0000313|EMBL:APR74306.1}; OS Gracilaria firma. OG Plastid {ECO:0000313|EMBL:APR74306.1}. OC Eukaryota; Rhodophyta; Florideophyceae; Rhodymeniophycidae; Gracilariales; OC Gracilariaceae; Gracilaria. OX NCBI_TaxID=2510791 {ECO:0000313|EMBL:APR74306.1}; RN [1] {ECO:0000313|EMBL:APR74306.1} RP NUCLEOTIDE SEQUENCE. RA Ng P.-K., Lin S.-M.; RL Submitted (JUL-2016) to the EMBL/GenBank/DDBJ databases. RN [2] {ECO:0000313|EMBL:APR74306.1} RP NUCLEOTIDE SEQUENCE. RX PubMed=28061748; DOI=10.1186/s12864-016-3453-0; RA Ng P.K., Lin S.M., Lim P.E., Liu L.C., Chen C.M., Pai T.W.; RT "Complete chloroplast genome of Gracilaria firma (Gracilariaceae, RT Rhodophyta), with discussion on the use of chloroplast phylogenomics in the RT subclass Rhodymeniophycidae."; RL BMC Genomics 18:40-40(2017). CC -!- FUNCTION: Component of the cytochrome b6-f complex, which mediates CC electron transfer between photosystem II (PSII) and photosystem I CC (PSI), cyclic electron flow around PSI, and state transitions. CC {ECO:0000256|ARBA:ARBA00003068, ECO:0000256|HAMAP-Rule:MF_00633}. CC -!- COFACTOR: CC Name=heme b; Xref=ChEBI:CHEBI:60344; CC Evidence={ECO:0000256|HAMAP-Rule:MF_00633}; CC Note=Binds 2 heme b groups non-covalently with two histidine residues CC as axial ligands. {ECO:0000256|HAMAP-Rule:MF_00633}; CC -!- COFACTOR: CC Name=heme c; Xref=ChEBI:CHEBI:61717; CC Evidence={ECO:0000256|HAMAP-Rule:MF_00633}; CC Note=Binds one heme group covalently by a single cysteine link with no CC axial amino acid ligand. This heme was named heme ci. CC {ECO:0000256|HAMAP-Rule:MF_00633}; CC -!- SUBUNIT: The 4 large subunits of the cytochrome b6-f complex are CC cytochrome b6, subunit IV (17 kDa polypeptide, PetD), cytochrome f and CC the Rieske protein, while the 4 small subunits are PetG, PetL, PetM and CC PetN. The complex functions as a dimer. {ECO:0000256|ARBA:ARBA00025834, CC ECO:0000256|HAMAP-Rule:MF_00633}. CC -!- SUBCELLULAR LOCATION: Cellular thylakoid membrane {ECO:0000256|HAMAP- CC Rule:MF_00633}; Multi-pass membrane protein {ECO:0000256|HAMAP- CC Rule:MF_00633}. Membrane {ECO:0000256|ARBA:ARBA00004141}; Multi-pass CC membrane protein {ECO:0000256|ARBA:ARBA00004141}. CC -!- MISCELLANEOUS: Heme 1 (or BH or b566) is high-potential and absorbs at CC about 566 nm, and heme 2 (or BL or b562) is low-potential and absorbs CC at about 562 nm. {ECO:0000256|HAMAP-Rule:MF_00633}. CC -!- SIMILARITY: Belongs to the cytochrome b family. PetB subfamily. CC {ECO:0000256|HAMAP-Rule:MF_00633}. 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; KX601051; APR74306.1; -; Genomic_DNA. DR AlphaFoldDB; A0A1P8D674; -. DR GO; GO:0009536; C:plastid; IEA:UniProtKB-KW. DR GO; GO:0042651; C:thylakoid membrane; IEA:UniProtKB-UniRule. DR GO; GO:0045158; F:electron transporter, transferring electrons within cytochrome b6/f complex of photosystem II activity; IEA:UniProtKB-UniRule. DR GO; GO:0046872; F:metal ion binding; IEA:UniProtKB-KW. DR GO; GO:0015979; P:photosynthesis; IEA:UniProtKB-UniRule. DR GO; GO:0022904; P:respiratory electron transport chain; IEA:InterPro. DR CDD; cd00284; Cytochrome_b_N; 1. DR HAMAP; MF_00633; Cytb6_f_cytb6; 1. DR InterPro; IPR005797; Cyt_b/b6_N. DR InterPro; IPR023530; Cyt_B6_PetB. DR InterPro; IPR027387; Cytb/b6-like_sf. DR InterPro; IPR048259; Cytochrome_b_N_euk/bac. DR InterPro; IPR016174; Di-haem_cyt_TM. DR PANTHER; PTHR19271; CYTOCHROME B; 1. DR PANTHER; PTHR19271:SF16; CYTOCHROME B6; 1. DR Pfam; PF00033; Cytochrome_B; 1. DR PIRSF; PIRSF000032; Cytochrome_b6; 1. DR SUPFAM; SSF81342; Transmembrane di-heme cytochromes; 1. DR PROSITE; PS51002; CYTB_NTER; 1. PE 3: Inferred from homology; KW Electron transport {ECO:0000256|HAMAP-Rule:MF_00633}; KW Heme {ECO:0000256|HAMAP-Rule:MF_00633}; KW Iron {ECO:0000256|HAMAP-Rule:MF_00633}; KW Membrane {ECO:0000256|HAMAP-Rule:MF_00633, ECO:0000256|SAM:Phobius}; KW Metal-binding {ECO:0000256|HAMAP-Rule:MF_00633}; KW Photosynthesis {ECO:0000256|ARBA:ARBA00022531, ECO:0000256|HAMAP- KW Rule:MF_00633}; Plastid {ECO:0000313|EMBL:APR74306.1}; KW Transmembrane {ECO:0000256|HAMAP-Rule:MF_00633, ECO:0000256|SAM:Phobius}; KW Transmembrane helix {ECO:0000256|HAMAP-Rule:MF_00633, KW ECO:0000256|SAM:Phobius}; Transport {ECO:0000256|HAMAP-Rule:MF_00633}. FT TRANSMEM 32..58 FT /note="Helical" FT /evidence="ECO:0000256|SAM:Phobius" FT TRANSMEM 88..106 FT /note="Helical" FT /evidence="ECO:0000256|SAM:Phobius" FT TRANSMEM 118..138 FT /note="Helical" FT /evidence="ECO:0000256|SAM:Phobius" FT TRANSMEM 184..206 FT /note="Helical" FT /evidence="ECO:0000256|SAM:Phobius" FT DOMAIN 4..215 FT /note="Cytochrome b/b6 N-terminal region profile" FT /evidence="ECO:0000259|PROSITE:PS51002" FT BINDING 35 FT /ligand="heme c" FT /ligand_id="ChEBI:CHEBI:61717" FT /note="covalent" FT /evidence="ECO:0000256|HAMAP-Rule:MF_00633" FT BINDING 86 FT /ligand="heme b" FT /ligand_id="ChEBI:CHEBI:60344" FT /ligand_label="2" FT /ligand_part="Fe" FT /ligand_part_id="ChEBI:CHEBI:18248" FT /note="axial binding residue" FT /evidence="ECO:0000256|HAMAP-Rule:MF_00633" FT BINDING 100 FT /ligand="heme b" FT /ligand_id="ChEBI:CHEBI:60344" FT /ligand_label="1" FT /ligand_part="Fe" FT /ligand_part_id="ChEBI:CHEBI:18248" FT /note="axial binding residue" FT /evidence="ECO:0000256|HAMAP-Rule:MF_00633" FT BINDING 187 FT /ligand="heme b" FT /ligand_id="ChEBI:CHEBI:60344" FT /ligand_label="2" FT /ligand_part="Fe" FT /ligand_part_id="ChEBI:CHEBI:18248" FT /note="axial binding residue" FT /evidence="ECO:0000256|HAMAP-Rule:MF_00633" FT BINDING 202 FT /ligand="heme b" FT /ligand_id="ChEBI:CHEBI:60344" FT /ligand_label="1" FT /ligand_part="Fe" FT /ligand_part_id="ChEBI:CHEBI:18248" FT /note="axial binding residue" FT /evidence="ECO:0000256|HAMAP-Rule:MF_00633" SQ SEQUENCE 215 AA; 24180 MW; 116A1B837B522574 CRC64; MGKVYDWFEE RLEIQAIADD ITSKYVPPHV NIFYCIGGIV FTSFLIQVAS GFAMTFYYRP TVAEAFSSVE YIMTDVNFGW LIRSIHRWSA SMMVLMLILH MFRVYLTGGF KKPRELTWVT GVILAVLTVS FGVTGYSLPW DQIGYWAVKI VTGVPEAIPL VGASIVELLR GGVSVGQGTL TRFYSLHTFV LPLLTAVFML MHFLMIRKQG ISGPL //